Copolymer of 1,3,7-octatriene and isoprene, hydride thereof, and method for producing said copolymer

ABSTRACT

The present invention provides a copolymer of 1,3,7-octatriene and isoprene having a narrow molecular weight distribution (Mw/Mn) and a hydride thereof. Furthermore, in a production method of a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, high raw material conversions are achieved for a short polymerization time. Specifically, the copolymer is a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene and is a copolymer having a molecular weight distribution (Mw/Mn) of less than 1.44, or the like.

FIELD OF THE INVENTION

The present invention relates to a copolymer of 1,3,7-octatriene and isoprene and a hydride thereof, and to a method of producing the copolymer.

BACKGROUND OF THE INVENTION

For producing films, adhesives, elastic bodies, fibers, foamed bodies, and so on, it is preferred to use a flexible, elastic, and tough polymer, and it is known that a polymer having a glass transition temperature lower than a use temperature thereof (usually a room temperature, e.g., about 25° C.) is suitable. As the polymer having a glass transition temperature lower than room temperature, a thermoplastic resin is exemplified, and as a raw material of the thermoplastic resin, butadiene which is inexpensive and easily utilizable is frequently utilized. However, in order to improve physical properties of the films, adhesives, elastic bodies, fibers, foamed bodies, and so on, there is a limit because the same raw material is used, and therefore, conjugated diene compounds which are not often used so far are interested. 1,3,7-Octatriene is one of such conjugated diene compounds.

A polymer containing a structural unit derived from 1,3,7-octatriene has a terminal double bond in a side chain thereof, and therefore, it can be denatured through various reactions, for example, epoxidation, halogenation, and graft polymerization with other low-molecular compound. In addition, maleic anhydride, acrolein, or the like can also be added while utilizing reactivity of the double bond existing in the polymer. The thus-obtained chemically denatured polymer is expected to be spread as a functional material, such as an adhesive and a lubricating agent.

However, there are very few reported cases regarding polymers containing a structural unit derived from 1,3,7-octatriene. For example, there are disclosed a polymerization method of 1,3,7-octatriene by using an anionic polymerization initiator (see PTL 1); a polymerization method of 1,3,7-octatriene by using a cationic polymerization initiator (see PTL 2); and a polymerization method of 1,3,7-octatriene by using a titanium-based Ziegler-type catalyst (see NPL 1). However, as for a copolymer of 1,3,7-octatriene and other conjugated diene compound, there is disclosed only a polymerization method using a neodymium-based Ziegler-type catalyst (see NPL 2).

In NPL 2 regarding the production method of a copolymer of 1,3,7-octatriene and other conjugated diene compound, as a copolymer formed from 1,3,7-octatriene and isoprene, there is disclosed a copolymer that is a copolymer in which the content of a structural unit derived from 1,3,7-octatriene is 21.0 mol % or less relative to a total amount of the structural unit derived from 1,3,7-octatriene and a structural unit of isoprene, and when the molecular weight distribution (Mw/Mn) is narrowest as 1.44, the weight average molecular weight (Mw) is 77,760, whereas when the weight average molecular weight (Mw) is largest as 201,300, the molecular weight distribution (Mw/Mn) expands to 1.83.

CITATION LIST Patent Literature

-   PTL 1: JP 49-16269 B -   PTL 2: JP 49-16268 B

Non-Patent Literature

-   NPL 1: The Journal of Organic Chemistry, Vol. 28, pp. 2699-2703     (1963) -   NPL 2: Advanced Synthesis & Catalysis, Vol. 350, pp. 431-438 (2008)

SUMMARY OF INVENTION Technical Problem

In order to enhance mechanical properties of a polymer, it is generally known that it is suitable to make the molecular weight distribution (Mw/Mn) narrow. In consequence, one of problems of the present invention is to provide a copolymer of 1,3,7-octatriene and isoprene having a narrow molecular weight distribution (Mw/Mn), which has not hitherto been produced, and a hydride thereof, and a method of producing the copolymer.

Now, in NPL 2, it is disclosed that in the case of copolymerizing 1,3,7-octatriene and isoprene in a mixing ratio of 1,3,7-octatriene of 5.5 mol % relative to a total amount of 1,3,7-octatriene and isoprene in the presence of a neodymium-based Ziegler-type catalyst, a copolymer having a weight average molecular weight (Mw) of 160,190 could be acquired in an isolated yield of 85% from the reaction liquid obtained through polymerization at 20° C. for 20 hours. That is, there was involved such a problem of difficulty in polymerization control that when merely using 1,3,7-octatriene only in a ratio of 5.5 mol % in combination with isoprene, the copolymerization reaction in the presence of a neodymium-based Ziegler-type catalyst becomes difficult to proceed, and in the case of polymerization at 20° C. for 20 hours, the isolated yield is limited to only 85%.

In the case where the conversion of 1,3,7-octatriene is high, it becomes simple and easy to perform separation and recovery of the copolymer from the raw materials. Furthermore, there is no concern that unreacted 1,3,7-octatriene is hydrogenated and converted into octane having an inexpensive unit price, and therefore, such is industrially preferred from the standpoint that an obtained copolymer can be subjected to hydrogenation reaction, etc. directly without going through a separation step. For that reason, the matter that high raw material conversions can be achieved for a short polymerization time is also one of problems of the present invention.

Solution to Problem

The present inventors made extensive and intensive investigations. As a result, it has been found that a cause of the difficulty of polymerization control resides in not 1,3,7-octatriene per se but impurities contained in 1,3,7-octatriene; and that by regulating the amount of the impurities to a predetermined value or less, the polymerization reaction of 1,3,7-octatriene and isoprene becomes easy to be controlled. Furthermore, it has also been noted that in the case where a total content of a peroxide and its decomposition product which may be mixed therein depending upon the production method of 1,3,7-octatriene is more than a predetermined amount, it becomes difficult to control the copolymerization of 1,3,7-octatriene and isoprene.

Then, the present inventors have found that the aforementioned problems can be solved by using 1,3,7-octatriene having not only a purity of more than 98.0% but also a total content of a peroxide and its decomposition product of 0.30 mmol/kg or less, thereby leading to accomplishment of the present invention.

Specifically, the present invention provides the following [1] to [26].

[1] A copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) of less than 1.44. [2] A copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) smaller than a value determined according to the following formula (i):

3.1569×10⁻⁶×[Weight average molecular weight (Mw)]+1.1945  (i).

[3] A copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having not only the content of the structural unit derived from 1,3,7-octatriene of more than 21.0 mol % relative to a total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene but also a molecular weight distribution (Mw/Mn) thereof of less than 2.06. [4] The copolymer as set forth in any of the above [1] to [3], having a weight average molecular weight (Mw) of 5,000 to 500,000. [5] The copolymer as set forth in any of the above [1] to [4], having a weight average molecular weight (Mw) of 20,000 to 500,000. [6] The copolymer as set forth in any of the above [1] to [5], having a weight average molecular weight (Mw) of 50,000 to 500,000. [7] The copolymer as set forth in any of the above [1] to [6], having a weight average molecular weight (Mw) of 210,000 to 500,000. [8] The copolymer as set forth in any of the above [1] to [7], not having a living anionic active species at a molecular end thereof. [9] The copolymer as set forth in any of the above [1] to [7], having a living anionic active species at a molecular end thereof. [10] A copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a living anionic active species at a molecular end thereof and having a molecular weight distribution (Mw/Mn) of 2.50 or less. [11] The copolymer as set forth in the above [10], having a weight average molecular weight (Mw) of 5,000 to 500,000. [12] The copolymer as set forth in any of the above [1] to [11], further containing a structural unit derived from a conjugated diene compound having 6 or more carbon atoms. [13] The copolymer as set forth in the claim [12], wherein the conjugated diene compound having 6 or more carbon atoms is at least one selected from the group consisting of 2,3-dimethyl-1,3-butadiene, 4,5-diethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2-benzyl-1,3-butadiene, 2-p-toluyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-diethyl-1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-diethyl-1,3-heptadiene, 3-butyl-1,3-octadiene, 2,3-dimethyl-1,3-octadiene, 4,5-diethyl-1,3-octathene, 1,3-cyclohexadiene, and myrcene. [14] A hydride of the copolymer as set forth in any of the above [1] to [8] and [10] to [13]. [15] A method of producing a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the method including a step of subjecting 1,3,7-octatriene having a purity, as determined by gas chromatography, of more than 98.0% and isoprene to anionic polymerization, wherein

impurities which may be contained in the 1,3,7-octatriene include at least one selected from the group consisting of a peroxide and its decomposition product, and a total content of the peroxide and its decomposition product in the 1,3,7-octatriene is 0.30 mmol/kg or less; and

the copolymer is satisfied with at least one of the following conditions I to III:

Condition I: a molecular weight distribution (Mw/Mn) is less than 1.44;

Condition II: a molecular weight distribution (Mw/Mn) is smaller than a value determined according to the following formula (i):

3.1569×10⁻⁶×[Weight average molecular weight (Mw)]+1.1945  (i); and

Condition III: not only the content of the structural unit derived from 1,3,7-octatriene is more than 21.0 mol % relative to a total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, but also a molecular weight distribution (Mw/Mn) thereof is less than 2.06.

[16] The method of producing a copolymer as set forth in the above [15], wherein the 1,3,7-octatriene has a purity, as determined by gas chromatography, of 98.5% or more. [17] The method of producing a copolymer as set forth in the above [15] or [16], wherein the anionic polymerization is carried out in the presence of a Lewis base. [18] The method of producing a copolymer as set forth in the above [17], wherein a molar ratio of the Lewis base to a polymerization initiator used for the anionic polymerization [(Lewis base)/(polymerization initiator)] is from 0.01 to 1,000. [19] The method of producing a copolymer as set forth in the above [17] or [18], wherein the Lewis base is a compound having at least one selected from the group consisting of an ether bond and a tertiary amino group in a molecule thereof. [20] The method of producing a copolymer as set forth in any of the above [17] to [19], wherein the Lewis base is a compound having one atom having an unshared electron pair. [21] The method of producing a copolymer as set forth in any of the above [17] to [19], wherein the Lewis base is a compound having two or more atoms having an unshared electron pair. [22] The method of producing a copolymer as set forth in the above [21], wherein the Lewis base has multidentate properties. [23] The method of producing a copolymer as set forth in any of the above [15] to [22], wherein a solid content concentration of a reaction liquid obtained after completion of the anionic polymerization is from 10 to 80% by mass. [24] The method of producing a copolymer as set forth in any of the above [15] to [23], wherein the anionic polymerization is carried out at −50 to 200° C. [25] The method of producing a copolymer as set forth in any of the above [15] to [24], wherein a conversion of the 1,3,7-octatriene after completion of the anionic polymerization, as determined by gas chromatography, is 80.0% or more. [26] The method of producing a copolymer as set forth in any of the above [15] to [25], wherein a conversion of the 1,3,7-octatriene after completion of the anionic polymerization, as determined by gas chromatography, is 88.0% or more.

Advantageous Effects of Invention

In accordance with the present invention, as for a copolymer of 1,3,7-octatriene and isoprene, it is possible to provide (I) a copolymer having a molecular weight distribution (Mw/Mn) of less than 1.44, (II) a copolymer having a molecular weight distribution (Mw/Mn) smaller than a value determined according to the aforementioned formula (i), and (III) a copolymer having not only the content of a structural unit derived from 1,3,7-octatriene of more than 21.0 mol % relative to a total amount of a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene but also a molecular weight distribution (Mw/Mn) thereof of less than 2.06; and a hydride of each of them.

Furthermore, in accordance with the present invention, it is possible to achieve a high conversion of each of the raw materials for a short polymerization time in the production of a copolymer of 1,3,7-octatriene and isoprene.

DESCRIPTION OF EMBODIMENTS

Hereinafter, all of embodiments in which the items mentioned in this specification are arbitrarily combined are included in the present invention. In addition, a lower limit value and an upper limit value in a numerical value range may be arbitrarily combined with a lower limit value and an upper limit value in other numerical value range, respectively.

[Copolymer]

The present invention relates to:

(I) a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) of less than 1.44 [hereinafter sometimes referred to as “copolymer (I)”],

(II) a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) smaller than a value determined according to the following formula (i) [hereinafter sometimes referred to as “copolymer (II)”]

3.1569×10⁻⁶×[Weight average molecular weight (Mw)]+1.1945  (i), and

(III) a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having not only the content of a structural unit derived from 1,3,7-octatriene (mol %; sometimes referred to as “1,3,7-octatriene content a”) of more than 21.0 mol % relative to a total amount of a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene but also a molecular weight distribution (Mw/Mn) thereof of less than 2.06 [hereinafter sometimes referred to as “copolymer (III)”].

These copolymers (I) to (III) are hereinafter sometimes referred collectively to as “copolymer of the present invention”.

In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are each a molecular weight as expressed in terms of standard polystyrene as determined by means of gel permeation chromatography (GPC) measurement, and more specifically, they are each a value as measured by the measurement method described in the section of Examples. In addition, the molecular weight distribution (Mw/Mn) is a value as calculated therefrom.

In the case of incorporating the copolymer of the present invention in a composition, in order to suppress bleed-out of the copolymer, it is preferred that not only the weight average molecular weight (Mw) of the copolymer of the present invention is high, but also the molecular weight distribution (Mw/Mn) thereof is narrow. But, in general, when the weight average molecular weight (Mw) is made high, the molecular weight distribution (Mw/Mn) tends to become broad. When the molecular weight distribution (Mw/Mn) is broad, a low molecular weight material coexists, thereby possibly causing the bleed-out. On the other hand, the present invention is able to provide a copolymer in which the molecular weight distribution (Mw/Mn) is kept narrow, and therefore, its industrial value is large.

The copolymer of the present invention can be produced by using, as a raw material, 1,3,7-octatriene having not only a purity of more than 98.0% but also a total content of a peroxide and its decomposition product of 0.30 mmol/kg or less. In particular, the copolymer of the present invention can be produced by performing anionic polymerization using such a raw material. By using such a raw material, a high conversion of the raw material can be achieved for a short polymerization time.

The purity of 1,3,7-octatriene is preferably 98.5% or more, more preferably 98.8% or more, and still more preferably 99.0% or more. Here, in the present invention, the purity of 1,3,7-octatriene is obtained by calculating the sum total of peak areas capable of being assigned to the whole of octatrienes by means of an analysis of gas chromatography and determining a percentage of a peak area of 1,3,7-octatriene relative to the sum total of these peak areas, and more specifically, it is one determined by a method described in the section of Examples. Here, the whole of octatrienes means all of 1,3,7-octatriene and double bond isomers thereof, such as 1,3,6-octatriene, 2,4,6-octatriene, and 1,4,6-octatriene.

Examples of the impurities which may be included in 1,3,7-octatriene include at least one selected from the group consisting of a peroxide and its decomposition product. A total content of the peroxide and its decomposition product in the 1,3,7-octatriene is preferably 0.30 mmol/kg or less, more preferably 0.15 mmol/kg or less, and still more preferably 0.10 mmol/kg or less (provided that one of them may be 0 mmol/kg). Here, in the present invention, the total content of the peroxide and its decomposition product in the 1,3,7-octatriene is a value determined by titrating iodine (12) generated by allowing potassium iodide to act on 1,3,7-octatriene with sodium thiosulfate, and more specifically, it is one determined by a method described in the section of Examples. Examples of the peroxide include 5-hydroperoxy-1,3,7-octatriene and 6-hydroperoxy-1,3,7-octatriene; and in addition, though the decomposition product of a peroxide is not particularly limited so long as it is a compound capable of being produced through decomposition of 5-hydroperoxy-1,3,7-octatriene or 6-hydroperoxy-1,3,7-octatriene, or the like, examples thereof include 5-hydroxy-1,3,7-octatriene and 6-hydroxy-1,3,7-octatriene. These are impurities which may be produced through oxygen oxidation of 1,3,7-octatriene. As the peroxide and its decomposition product, in particular, 5-hydroperoxy-1,3,7-octatriene, 6-hydroperoxy-1,3,7-octatriene, 5-hydroxy-1,3, 7-octatriene, and 6-hydroxy-1,3,7-octatriene are an important compound.

As for the 1,3,7-octatriene, it is extremely difficult to perform distillation separation from a by-product, for example, 4-vinylcyclohexene and 1,3,6-octatriene, and therefore, in general, 1,3,7-octatriene having a purity of more than 98.0% is not easily obtainable, and its purity is typically liable to be 97% or less. But, by carrying out the method described in JP 2016-216385 A or JP 47-17703 A, it is possible to produce 1,3,7-octatriene having a purity of more than 98.0%, and in the present invention, this 1,3,7-octatriene can be utilized. Nevertheless the 1,3,7-octatriene having a purity of more than 98.0% exists like this, those skilled in the art recognized that to begin with, the polymerization control of 1,3,7-octatriene is difficult, and therefore, they have not hitherto considered carrying out the polymerization reaction using, as the raw material, 1,3,7-octatriene whose purity has been especially increased to more than 98.0%. However, during the development made by the present inventors regarding the copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, it has been found that the copolymer of the present invention can be produced in a high conversion for a short time by using, as the raw material, 1,3,7-octatriene having a purity of more than 98.0%, in particular, 1,3,7-octatriene having not only a purity of more than 98.0% but also a total content of a peroxide and its decomposition product of 0.30 mmol/kg or less.

With respect to the copolymer of the present invention, a weight average molecular weight (Mw) thereof is preferably 5,000 to 500,000, more preferably 20,000 to 500,000, still more preferably 50,000 to 500,000, and especially preferably 210,000 to 500,000.

In the copolymer of the present invention, though the content of the structural unit derived from 1,3,7-octatriene (1,3,7-octatriene content a) relative to the total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene is not particularly limited except for the copolymer (III), it is preferably 3 to 97 mol %, more preferably 5 to 96 mol %, may be 20 to 96 mol %, may be 20 to 70 mol %, and may be 20 to 40 mol %.

The copolymer of the present invention has only to contain a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene and may further contain a structural unit derived from other conjugated diene compound. In addition, the copolymer of the present invention may be a copolymer formed of only a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene. In the case where the copolymer of the present invention contains a structural unit derived from other conjugated diene compound, the content is preferably 50 mol % or less, may be 30 mol % or less, may be 20 mol % or less, may be 10 mol % or less, and may be 5 mol % or less based on a total amount of the structural unit derived from 1,3,7-octatriene, the structural unit derived from isoprene, and the structural unit derived from other conjugated diene.

The other conjugated diene compound is preferably a conjugated diene compound having 6 or more carbon atoms, and more preferably at least one selected from the group consisting of 2,3-dimethyl-1,3-butadiene, 4,5-diethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2-benzyl-1,3-butadiene, 2-p-toluyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2, 3-diethyl-1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-diethyl-1,3-heptadiene, 3-butyl-1,3-octadiene, 2,3-dimethyl-1,3-octadiene, 4, 5-diethyl-1,3-octadiene, 1,3-cyclohexadiene, and myrcene (7-methyl-3-methyleneocta-1,6-diene).

The copolymer of the present invention may or may not be denatured through copolymerization with an anionic polymerizable compound. In the case where the copolymer of the present invention is denatured with an anionic polymerizable compound, the content of the structural unit derived from the anionic polymerizable compound is preferably 5 mol % or less, and more preferably 3 mol % or less in the whole of structural units.

The anionic polymerizable compound is not particularly limited so long as it is a compound other than 1,3,7-octatriene, isoprene, and the other conjugated diene compound and is a compound capable of undergoing anionic polymerization. Examples thereof include aromatic vinyl compounds, such as styrene, 2-chlorostyrene, 4-chlorostyrene, α-methylstyrene, α-methyl-4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-isopropylstyrene, 4-tert-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(4-phenyl-n-butyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene, 1,2-divinyl-3,4-dimethylbenzene, 2,4-divinylbiphenyl, 1,3-divinylnaphthalene, 1,2,4-trivinylbenzene, 3,5,4′-trivinylbiphenyl, 1,3,5-trivinylnaphthalene, and 1,5,6-trivinyl-3, 7-diethylnaphthalene; α,β-unsaturated nitriles, such as acrylonitrile, methacrylonitrile, and ethacrylonitrile; α,β-unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, 3-methylcrotonic acid, 3-butenoic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid; α,β-unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl itaconate, diethyl itaconate, and dibutyl itaconate; and acrylamides, such as N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-butylacrylamide, N-octylacrylamide, N-phenylacrylamide, N-glycidylacrylamide, N,N′-ethylenebisacrylamide, N,N-dim ethylacrylamide, N-ethyl-N-methylacrylamide, N,N-diethylacrylamide, N,N-dipropylacrylamide, N,N-dioctylacrylamide, N,N-diphenylacrylamide, N-ethyl-N-glycidylacrylamide, N,N-diglycidylacrylamide, N-methyl-N-(4-glycidyloxybutyl)acrylamide, N-methyl-N-(5-glycidyloxypentyl)acrylamide, N-methyl-N-(6-glycidyloxyhexyl)acrylamide, N-acryloylpyrrolidine, N-acryloyl-L-proline methyl ester, N-acryloylpiperidine, N-acryloylmorpholine, 1-acryloylimidazole, N,N′-diethyl-N,N′-ethylenebisacrylamide, N,N′-dimethyl-N,N′-hexamethylenebisacrylamide, and di(N,N′-ethylene)bisacrylamide.

The anionic polymerizable compounds may be used alone or may be used in combination of two or more thereof.

The copolymer of the present invention may or may not contain a structural unit derived from a coupling agent. In the case where the copolymer of the present invention contains a structural unit derived from a coupling agent, the content of the structural unit derived from a coupling agent is preferably 2.5 mol % or less, and more preferably 1.0 mol % or less in the whole of structural units.

Examples of the coupling agent include dichloromethane, dibromomethane, dichloroethane, dibromoethane, dibromobenzene, and phenyl benzoate.

(Binding Mode)

In the copolymer of the present invention, as a representative binding mode of 1,3,7-octatriene, a 1,2-bond, a 3,4-bond, a 1,4-bond, and a 4,1-bond are included, and the binding order and the content ratio of the respective binding modes are not particularly limited. In the present invention, the 1,4-bond and the 4,1-bond are considered to be identical with each other.

With respect to the binding mode of 1,3,7-octatriene, the content ratio of the 1,2-bond relative to the whole of binding modes is preferably 35 to 65 mol %, more preferably 40 to 60 mol %, and still more preferably 40 to 50 mol %. The content ratio of the 1,4-bond relative to the whole of binding modes is preferably 20 to 65 mol %, more preferably 40 to 60 mol %, and still more preferably 45 to 60 mol %. Taking into consideration the aforementioned content ratio of the 1,2-bond and the aforementioned content ratio of the 1,4-bond, the content ratio of the 3,4-bond relative to the whole of binding modes becomes the remainder. Namely, the content ratio of the 3,4-bond relative to the whole of binding modes is determined from “100−[(content ratio of the 1,2-bond)+(content ratio of the 1,4-bond)]”.

As a representative binding mode of isoprene, a 1,2-bond, a 3,4-bond, and a 1,4-bond are included, and the binding order and the content ratio of the respective binding modes are not particularly limited.

With respect to the binding mode of isoprene, the content ratio of the 1,4-bond relative to the whole of binding modes is preferably 5 to 95 mol %, and more preferably 10 to 90 mol %. The content ratio of the 3,4-bond relative to the whole of binding modes is preferably 5 to 95 mol %, and more preferably 5 to 85 mol %. Taking into consideration the aforementioned content ratio of the 1,4-bond and the aforementioned content ratio of the 3,4-bond, the content ratio of the 1,2-bond relative to the whole of binding modes becomes the remainder.

Similarly, the binding mode of the other conjugated diene compound is not particularly limited, and the binding order and the content ratio of the respective binding modes are not particularly limited.

The ratio of each of the binding modes is determined by the ¹³C-NMR measurement. Specifically, it can be determined according to the method described in the section of Examples.

(Binding Form)

In the copolymer of the present invention, a binding form between the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, and in the case of further containing the structural unit derived from the other conjugated diene compound, a binding form thereamong, are not particularly limited; however, examples of the binding form include random, complete alternate, gradient, block, and tapered binding forms as well as combinations thereof, and a random binding form is preferred from the viewpoint of easiness of production.

With respect to the copolymer (I), the molecular weight distribution (Mw/Mn) is preferably 1.40 or less, more preferably 1.35 or less, still more preferably 1.30 or less, yet still more preferably 1.20 or less, especially preferably 1.15 or less, and most preferably 1.10 or less. Though a lower limit of the molecular weight distribution (Mw/Mn) is not particularly limited, it is typically 1.03 or more, and it often becomes 1.05 or more.

With respect to the copolymer (II), the formula (i) is one determined in the following manner. Using the weight average molecular weight (Mw) and the molecular weight distribution (Mw/Mn) of each of Entry 4 and Entry 6 in Table 1 of the aforementioned NPL 2, the weight average molecular weight (Mw) was taken on the abscissa, whereas the molecular weight distribution (Mw/Mn) was taken on the ordinate; a formula expressing a straight line passing through two points was determined; and a formula resulting from addition of a gradient of the straight line and a value of the intercept when the weight average molecular weight (Mw) is 0 was defined as the formula (i). The data of the foregoing non-patent literature are all located on the foregoing straight line or distributed above the straight line, and therefore, those beneath the foregoing straight line fall within a range not disclosed in the NPL 2.

Though the range of the weight average molecular weight (Mw) in the formula (i) is not particularly limited, it is preferably 1,000 to 300,000, more preferably 5,000 to 300,000, still more preferably 10,000 to 300,000, especially preferably 40,000 to 300,000, and most preferably 40,000 to 250,000.

With respect to the copolymer (III), the 1,3,7-octratriene content a is preferably 40 mol % or more, more preferably 60 mol % or more, still more preferably 70 mol % or more, especially preferably 80 mol % or more, and most preferably 90 mol % or more. Though an upper limit of the 1,3,7-octratriene content a is not particularly limited, it may be 99 mol % or less, may be 98 mol % or less, and may be 97 mol % or less.

With respect to the copolymer (III), the molecular weight distribution (Mw/Mn) is preferably 1.98 or less, more preferably 1.90 or less, still more preferably 1.80 or less, yet still more preferably 1.70 or less, especially preferably 1.50 or less, and most preferably 1.40 or less. Though a lower limit value of the molecular weight distribution (Mw/Mn) is not particularly limited, typically, it often becomes 1.05 or more.

On the occasion of producing the copolymer of the present invention through anionic polymerization as mentioned later, the copolymer at a stage after allowing a chain terminator to react after the polymerization reaction is a copolymer not having a living anionic active species at a molecular end thereof, and the present invention provides the foregoing copolymer.

On the occasion of producing the copolymer of the present invention through anionic polymerization as mentioned later, the copolymer at a stage before allowing a chain terminator to react after the polymerization reaction is a copolymer having a living anionic active species at a molecular end thereof (sometimes referred to as “living anionic copolymer”), and the present invention also provides the foregoing copolymer. In particular, with respect to the copolymer having a living anionic active species at a molecular end thereof, one having the molecular weight distribution (Mw/Mn) of 2.50 or less can be provided. The molecular weight distribution (Mw/Mn) is preferably 2.00 or less, more preferably 1.50 or less, still more preferably 1.40 or less, and especially preferably 1.15 or less.

(Hydride)

The copolymer of the present invention may also be a hydride of the aforementioned copolymer (in general, also referred to as “hydrogenation product”) from the viewpoints of heat resistance and weather resistance. In the case where the copolymer of the present invention is a hydride, though a hydrogenation rate thereof is not particularly limited, in the copolymer, the carbon-carbon double bond is hydrogenated to an extent of preferably 80 mol % or more, more preferably 85 mol % or more, still more preferably 90 mol % or more, especially preferably 93 mol % or more, and most preferably 95 mol % or more. The foregoing value is sometimes referred to as “hydrogenation rate”. Though an upper limit value of the hydrogenation rate is not particularly limited, it may be 99 mol % or less.

The hydrogenation rate is determined by the ¹H-NMR measurement of the content of the carbon-carbon double bond after hydrogenation. More specifically, it can be determined according to the method described in the section of Examples.

[Production Method of Copolymer]

A production method of a copolymer of the present invention is a method of producing a copolymer (namely, the aforementioned copolymer of the present invention) containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the method including a step of subjecting 1,3,7-octatriene having a purity, as determined by gas chromatography, of more than 98.0% and isoprene to anionic polymerization, wherein

impurities which may be contained in the 1,3,7-octatriene include a peroxide and its decomposition product, and a total content of the peroxide and its decomposition product in the 1,3,7-octatriene is 0.30 mmol/kg or less; and

the copolymer is satisfied with at least one of the following conditions I to III;

Condition I; a molecular weight distribution (Mw/Mn) is less than 1.44;

Condition II; a molecular weight distribution (Mw/Mn) is smaller than a value determined according to the aforementioned formula (i); and

Condition III; not only the content of the structural unit derived from 1,3,7-octatriene is more than 21.0 mol % relative to a total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, but also a molecular weight distribution (Mw/Mn) thereof is less than 2.06.

The anionic polymerization method is not particularly limited, and a known anionic polymerization method is applicable.

For example, an anionic polymerization initiator is fed into a mixture of 1,3,7-octatriene and isoprene, and the aforementioned conjugated diene compound which is optionally used (the raw materials to be subjected to polymerization reaction will be hereinafter sometimes referred to as “raw material monomers”), to undergo polymerization reaction, thereby forming a copolymer having a living anionic active species in the reaction system. Subsequently, a polymerization terminator is added thereto, thereby producing a random copolymer.

Furthermore, a block copolymer may be produced by feeding the anionic polymerization initiator to any one of the raw material monomers and then adding the remaining raw material monomer or monomers to form a copolymer having a living anionic active species, followed by adding a polymerization terminator.

A Lewis base and a solvent may be used, if desired.

For the purpose of suppressing invasion of water and oxygen, etc., which hinder the polymerization reaction, into the reaction system, for example, it is preferred to carry out the polymerization reaction in the interior of a reactor pressurized with an inert gas. When the polymerization reaction is carried out in an inert gas atmosphere, consumption of the anionic polymerization initiator and a growing terminal anion by the reaction with water or oxygen can be suppressed, so that the polymerization reaction can be precisely controlled. Here, the growing terminal anion refers to an anion which the copolymer existing in the reaction system during the polymerization reaction has at a molecular end thereof, and hereinafter, the same is applicable.

It is preferred that 1,3,7-octatriene, isoprene, the aforementioned conjugated diene compound, an anionic polymerization initiator as mentioned later, a Lewis base as mentioned later, a solvent as mentioned later, and so on, which are used in the production of the copolymer, do not substantially contain substances which react with the growing terminal anion to hinder the polymerization reaction, for example, oxygen, water, a hydroxy compound, a carbonyl compound, and an alkyne compound, and it is preferred that those materials are stored under a shading condition in an inert gas atmosphere of nitrogen, argon, helium, or the like.

Each of 1,3,7-octatriene, isoprene, the anionic polymerization initiator, the Lewis base, and so on may be used upon being diluted with a solvent or may be used without being diluted with a solvent.

As mentioned above, an important point in the production method of a copolymer of the present invention resides in the use of 1,3,7-octatriene having a purity of more than 98.0% and having a total content of a peroxide and its decomposition product of 0.30 mmol/kg or less (more preferably those as mentioned above).

Simultaneously, it is preferred to use compounds each having a high purity for isoprene and the aforementioned conjugated diene compound; however, with respect to isoprene and the conjugated diene compound, it is sufficient so long as isoprene and the conjugated diene compound each have a purity equal to or higher than that of each of isoprene and the conjugated diene compound to be used on the occasion of the usual polymerization thereof. In general, the purity of each of isoprene and the conjugated diene compound as determined by gas chromatography is preferably 99% or more. In addition thereto, it is more preferred to use isoprene and the conjugated diene compound, each of which does not substantially contain an alkyne, such as acetylene, an alkene, such as ethylene, and a hydrocarbon compound having a functional group, such as a carbonyl group and a hydroxy group.

(Anionic Polymerization Initiator)

The production method of a copolymer of the present invention utilizes the anionic polymerization, and therefore, an anionic polymerization initiator is used. The anionic polymerization initiator is not limited in terms of its kind so long as it is able to initiate the anionic polymerization.

As the anionic polymerization initiator, an organic alkali metal compound which is generally used in anionic polymerization of an aromatic vinyl compound and a conjugated diene compound can be used. Examples of the organic alkali metal compound include organic lithium compounds, such as methyllithium, ethyllithium, propyllithium, is opropyllithium, butyllithium, sec-butyllithium, tert-butyllithium, isobutyllithium, pentyllithium, hexyllithium, butadienyllithium, cyclohexyllithium, phenyllithium, benzyllithium, p-toluyllithium, styryllithium, trimethylsilyllithium, 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4 dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene; and organic sodium compounds, such as methylsodium, ethylsodium, n-propylsodium, isopropylsodium, n-butylsodium, sec-butylsodium, tert-butylsodium, isobutylsodium, phenylsodium, sodium naphthalene, and cyclopentadienylsodium. Above all, n-butyllithium and sec-butyllithium are preferred. The organic alkali metal compounds may be used alone or may be used in combination of two or more thereof.

Though the use amount of the anionic polymerization initiator can be properly set according to the desired weight average molecular weight of the living anionic polymer or solid content concentration of the reaction liquid, for example, it is preferably 10 to 3,000, more preferably 50 to 2,500, still more preferably 100 to 2,500, and especially preferably 300 to 2,300 in terms of a molar ratio of the total amount of raw material monomers to the anionic polymerization initiator.

(Lewis Base)

In the production method of a copolymer of the present invention, from the viewpoint of controlling the polymerization reaction, in particular, from the viewpoint of obtaining a high conversion of 1,3,7-octatriene for a short time, a Lewis base may be used, and it is preferred to use a Lewis base. The Lewis base is not particularly limited in terms of its kind so long as it is an organic compound which does not substantially react with the anionic polymerization initiator and the growing terminal anion.

In the case of using the Lewis base, a molar ratio of the Lewis base to the polymerization initiator (anionic polymerization initiator) to be used for the anionic polymerization [(Lewis base)/(polymerization initiator)] is preferably 0.01 to 1,000, more preferably 0.01 to 400, still more preferably 0.1 to 50, and especially preferably 0.1 to 20. When the foregoing molar ratio falls within this range, a high conversion of 1,3,7-octatriene is readily achieved for a short time.

As the Lewis base, there is exemplified (i) a compound having at least one selected from the group consisting of an ether bond and a tertiary amino group in a molecule thereof [hereinafter referred to as “Lewis base (i)”]. Examples of the Lewis base (i) include (i-1) a compound having one atom having an unshared electron pair [hereinafter referred to as “Lewis base (i-1)] and (i-2) a compound having two or more atoms having an unshared electron pair [hereinafter referred to as “Lewis base (i-2)].

The Lewis base may be one having monodentate properties or may be one having multidentate properties. In addition, the Lewis base may be used alone or may be used in combination of two or more thereof.

(Lewis Base (i))

In the Lewis base (i), specific examples of the Lewis base (i-1) include non-cyclic monoethers, such as dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether, dipropyl ether, diisopropyl ether, butyl methyl ether, tert-butyl methyl ether, dibutyl ether, dioctyl ether, ethyl phenyl ether, and diphenyl ether; cyclic monoethers having preferably 2 to 40 carbon atoms in total (more preferably 2 to 20 carbon atoms in total), such as tetrahydrofuran and tetrahydropyran; and tertiary monoamines having preferably 3 to 60 carbon atoms in total (more preferably 3 to 15 carbon atoms in total), such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, triisobutylamine, tri-sec-butylamine, tri-tert-butylamine, tri-tert-hexylamine, tri-tert-octylamine, tri-tert-decylamine, tri-tert-dodecylamine, tri-tert-tetradecylamine, tri-tert-hexadecylamine, tri-tert-octadecylamine, tri-tert-tetracosanylamine, tri-tert-octacosanylamine, 1-methyl-1-amino-cyclohexane, tripentylamine, triisopentylamine, trineopentylamine, trihexylamine, triheptylamine, trioctylamine, triphenylamine, tribenzylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylisopropylamine, N,N-dimethylbutylamine, N,N-dimethylisobutylamine, N,N-dimethyl-sec-butylamine, N,N-dimethyl-tert-butylamine, N,N-dimethylpentylamine, N,N-dimethylisopentylamine, N,N-dimethylneopentylamine, N,N-dimethylhexylamine, N,N-dimethylheptylamine, N,N-dimethyloctylamine, N,N-dimethylnonylamine, N,N-dimethyldecylamine, N,N-dimethylundecylamine, N,N-dimethyldodecylamine, N,N-dimethylphenylamine, N,N-dimethylbenzylamine, N,N-diethylmonomethylamine, N,N-dipropylmonomethylamine, N,N-diisopropylmonomethylamine, N,N-dibutylmonomethylamine, N,N-diisobutylmonomethylamine, N,N-di-sec-butylmonomethylamine, N,N-di-tert-butylmonomethylamine, N,N-dipentylmonomethylamine, N,N-diisopentylmonomethylamine, N,N-dineopentylmonomethylamine, N,N-dihexylmonomethylamine, N,N-diheptylmonomethylamine, N,N-dioctylmonomethylamine, N,N-dinonylmonomethylamine, N,N-didecylmonomethylamine, N,N-diundecylmonomethylamine, N,N-didodecylmonomethylamine, N,N-diphenylmonomethylamine, N,N-dibenzylmonomethylamine, N,N-dipropylmonomethylamine, N,N-diisopropylmonoethylamine, N,N-dibutylmonoethylamine, N,N-diisobutylmonoethylamine, N,N-di-sec-butylmonoethylamine, N,N-di-tert-butylmonoethylamine, N,N-dipentylmonoethylamine, N,N-diisopentylmonoethylamine, N,N-dineopentylmonoethylamine, N,N-dihexylmonoethylamine, N,N-diheptylmonoethylamine, N,N-dioctylmonoethylamine, N,N-dinonylmonoethylamine, N,N-didecylmonoethylamine, N,N-diundecylmonoethylamine, N,N-didodecylmonoethylamine, N,N-diphenylmonoethylamine, N,N-dibenzylmonoethylamine, N,N-dimethylaniline, N,N-diethylaniline, N-ethylpiperazine, N-methyl-N-ethylaniline, and N-methylmorpholine.

The Lewis base (i-1) is a Lewis base having monodentate properties to the metal atom of the anionic polymerization initiator.

From the viewpoint of controlling the polymerization reaction, in particular, from the viewpoint of obtaining a high conversion of 1,3,7-octatriene for a short time, diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, triethylamine, and N,N-dimethylethylamine are preferred as the Lewis base (i-1).

In the case of using the Lewis base (i-1), a molar ratio of the atom having an unshared electron pair in the Lewis base (i-1) to the metal atom of the polymerization initiator used for the anionic polymerization [(atom having an unshared electron pair)/(metal atom of polymerization initiator)] is preferably 0.01 to 1,000, more preferably 0.1 to 500, still more preferably 2 to 300, especially preferably 2 to 100, and most preferably 2 to 50. When the foregoing molar ratio falls within this range, a high conversion of 1,3,7-octatriene is readily achieved for a short time.

In the Lewis base (i), specific examples of the Lewis base (i-2) include non-cyclic diethers having preferably 4 to 80 carbon atoms in total (more preferably 4 to 40 carbon atoms in total), such as 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane, 1,2-dibutoxyethane, 1,2-diphenoxyethane, 1,2-dimethoxypropane, 1,2-diethoxypropane, 1,2-diphenoxypropane, 1,3-dimethoxypropane, 1,3-diethoxypropane, 1,3-diisopropoxypropane, 1,3-dibutoxypropane, and 1,3-diphenoxypropane; cyclic diethers having preferably 4 to 80 carbon atoms in total (more preferably to 40 carbon atoms in total), such as 1,4-dioxane and 2,2-di(tetrahydrofuryl)propane; non-cyclic polyethers having preferably 6 to 40 carbon atoms in total (more preferably 6 to 20 carbon atoms in total), such as diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dibutylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, dibutylene glycol diethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tributylene glycol dimethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, tributylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, tetrabutylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetrapropylene glycol diethyl ether, and tetrabutylene glycol diethyl ether; and polyamines having preferably 6 to 122 carbon atoms in total (more preferably 6 to 32 carbon atoms in total, and still more preferably 6 to 15 carbon atoms in total), such as N,N,N′,N′-tetramethylethylenediamine, N,N,N′,N′-tetraethylethylenediamine, N,N,N,N″,N″-pentamethyldiethylenetriamine, and tris [2-(dimethylamino)ethyl]amine.

The Lewis base (i-2) includes a Lewis base having monodentate properties to the metal atom of the anionic polymerization initiator and a Lewis base having multidentate properties to the metal atom of the anionic polymerization initiator.

From the viewpoint of controlling the polymerization reaction, in particular, from the viewpoint of obtaining a high conversion of 1,3,7-octatriene for a short time, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-diisopropoxyethane, 2,2-di(tetrahydrofuryl)propane, N,N,N′,N′-tetramethylethylenediamine, and N,N,N′,N′-tetraethylethylenediamine are preferred as the Lewis base (i-2).

In the case of using the Lewis base (i-2), the Lewis base having monodentate properties to the metal atom of the anionic polymerization initiator and the Lewis base having multidentate properties (for example, bidentate properties) to the metal atom of the anionic polymerization initiator are different from each other with respect to a preferred use amount. The Lewis base (i-2) has two or more atoms having an unshared electron pair. In this regard, when attention is paid to two atoms having an unshared electron pair, in the case where the shortest crosslinked carbon number connecting them is 1 (for example, —O—CH₂—O— and >N—CH₂—N<) or 3 or more (for example, —O—C₃H₆—O—, >N—C₄H₈—N<, and —O—C₃H₆—N<), each of the atoms tends to have monodentate properties. On the other hand, when attention is similarly paid to two atoms having an unshared electron pair, in the case where the shortest crosslinked carbon number connecting them is 2 (for example, —O—C₂H₄—O— and >N—C₂H₄—N<), there is a tendency that the two atoms having those unshared electron pairs are subjected to a multidentate arrangement (bidentate arrangement) to one metal atom of the anionic polymerization initiator.

In the case where the Lewis base (i-2) is a Lewis base having monodentate properties, a molar ratio of the atom having an unshared electron pair in the Lewis base (i-2) to the metal atom of the polymerization initiator to be used for the anionic polymerization [(atom having an unshared electron pair)/(metal atom of polymerization initiator)] is preferably 0.01 to 1,000, more preferably 0.1 to 500, still more preferably 2 to 300, especially preferably 2 to 100, and most preferably 2 to 50. When the foregoing molar ratio falls within this range, a high conversion of 1,3,7-octatriene is readily achieved for a short time.

On the other hand, in the case where the Lewis base (i-2) is a Lewis base having multidentate properties (bidentate properties), a molar ratio of the atom having an unshared electron pair in the Lewis base (i-2) to the metal atom of the polymerization initiator to be used for the anionic polymerization [(atom having an unshared electron pair)/(metal atom of polymerization initiator)] is preferably 0.01 to 50, more preferably 0.1 to 10, still more preferably 0.1 to 5, and especially preferably 0.3 to 4. When the foregoing molar ratio falls within this range, a high conversion of 1,3,7-octatriene is readily achieved for a short time.

In the case of a Lewis base having both monodentate properties and multidentate properties (bidentate properties), it is preferred to determine the use amount of the Lewis base by combing an atom having unshared electron pair having monodentate properties with two or more atoms having unshared electron pair having multidentate properties (bidentate properties), paying attention thereto, and referring to the aforementioned description.

(Solvent)

Though the production method of a copolymer of the present invention can be carried out in the absence of a solvent, for the purpose of efficiently removing polymerization heat, it is preferred to carry out the production in the presence of a solvent.

Though the solvent is not particularly limited in terms of its kind so long as it does not substantially react with the anionic polymerization initiator and the growing terminal anion, a hydrocarbon-based solvent is preferred from the viewpoint of precisely controlling the polymerization time and the conversion with the Lewis base.

Examples of the hydrocarbon-based solvent include saturated aliphatic hydrocarbons, such as isopentane (27.9° C.; a boiling point at 1 atm, hereinafter the same), pentane (36.1° C.), cyclopentane (49.3° C.), hexane (68.7° C.), cyclohexane (80.7° C.), heptane (98.4° C.), isoheptane (90° C.), isooctane (99° C.), 2,2,4-trimethylpentane (99° C.), methylcyclohexane (101.1° C.), cycloheptane (118.1° C.), octane (125.7° C.), ethylcyclohexane (132° C.), methylcycloheptane (135.8° C.), nonane (150.8° C.), and decane (174.1° C.); and aromatic hydrocarbons, such as benzene (80.1° C.), toluene (110.6° C.), ethylbenzene (136.2° C.), p-xylene (138.4° C.), m-xylene (139.1° C.), o-xylene (144.4° C.), propylbenzene (159.2° C.), and butylbenzene (183.4° C.).

When a solvent having a boiling point of lower than that of 1,3,7-octatriene (boiling point: 125.5° C.) that is one of the raw material monomers is used, the polymerization heat can be efficiently removed by means of reflux condensation cooling of the solvent, and hence, such is preferred. From this viewpoint, isopentane (27.9° C.), pentane (36.1° C.), cyclopentane (49.3° C.), hexane (68.7° C.), cyclohexane (80.7° C.), heptane (98.4° C.), isoheptane (90° C.), isooctane (99° C.), 2,2,4-trimethylpentane (99° C.), methylcyclohexane (101.1° C.), cycloheptane (118.1° C.), benzene (80.1° C.), and toluene (110.6° C.) are preferred. Above all, from the same viewpoint, cyclohexane and n-hexane are more preferred.

The solvents may be used alone or may be used in combination of two or more thereof.

Though the use amount of the solvent is not particularly limited, it is regulated such that a solid content concentration of the reaction liquid obtained after completion of the anionic polymerization is preferably 10 to 80% by mass, more preferably 10 to 70% by mass, still more preferably 15 to 65% by mass, especially preferably 15 to 55% by mass, and most preferably 25 to 55% by mass. In addition, it is preferred to regulate the use amount of the solvent such that a concentration of the living anionic polymer in the reaction system is 5% by mass or more, and it is more preferred to regulate the use amount of the solvent such that the concentration of the living anionic polymer is 10 to 80% by mass. When the solvent is used in such an amount, the removal of polymerization heat can be achieved at a level suited for industrial production, and therefore, not only the polymerization time is readily shortened, but also a high conversion of 1,3,7-octatriene is readily achieved. Furthermore, when the solvent is used in such an amount, the molecular weight distribution is readily made narrow.

From the viewpoint of making the step of removing the solvent simple, the concentration of the solid content in the reaction liquid after completion of anionic polymerization may be adjusted to 35 to 80% by mass, and may be adjusted to 50 to 70% by mass.

(Reactor)

A type of a reactor is not particularly limited, a complete mixing type reactor, a tubular reactor, and a reaction apparatus in which two or more of these reactors are connected in series or in parallel can be used. From the viewpoint of producing a copolymer having a narrow molecular weight distribution (Mw/Mn) at a high solution viscosity, it is suitable to use a complete mixing type reactor. Though an impeller of the reactor is not particularly limited, examples thereof include a max blend blade, a full-zone blade, a paddle blade, a propeller blade, a turbine blade, a fan turbine blade, a Pfaudler blade, and a blue margin blade, and a combination of any two or more thereof may also be used. In the case where the viscosity of the obtained polymer solution is high, from the viewpoints of making the molecular weight distribution (Mw/Mn) narrow and promoting the jacket heat removal, it is preferred to use a max blend blade or a full-zone blade.

An agitation method may be either upper portion agitation or lower portion agitation.

A polymerization method is not particularly limited, and it may be carried out by all of batch, semi-batch, and continuous systems. For the purpose of heating and cooling of the solution in the inside of the reactor, the complete mixing type reactor may be provided with a jacket in the outside thereof, and a structure thereof is not particularly limited, and a known system can be adopted. In addition, for the purpose of increasing cooling heat transfer, if desired, a cooling baffle or a cooling coil, etc. may be attached to the inside of the reactor. Furthermore, a direct or indirect type reflux condenser may be attached to a gas phase portion. From the viewpoint of controlling the removal amount of polymerization heat, the reactor may be pressurized with an inert gas, or may be evacuated to atmospheric pressure or lower. In the case of reducing the internal pressure of the reactor to atmospheric pressure or lower, a pump for venting the inert gas may be installed via the reflux condenser. Though a structure of the reflux condenser is not particularly limited, it is preferred to use a multitubular reflux condenser. As for the reflux condenser, plural reflux condensers may be connected in series or in parallel, and a different coolant may be made to pass through each of the reflux condensers. A temperature of the colorant which is made to pass through the reflux condenser is not particularly limited within a range of from a temperature at which the solvent to be refluxed is not frozen to the reaction liquid temperature; however, so long as it is preferably −20 to 50° C., and more preferably 5 to 30° C., a large-sized refrigerating machine is not needed, and hence, such is economical.

(Polymerization Temperature)

Though the polymerization temperature is not particularly limited, it is preferred to carry out the polymerization within a range of from a temperature equal to or higher than the freezing points of the chemicals to a temperature equal to or lower than the temperatures at which the chemicals are not heat-decomposed. So long as the polymerization temperature is preferably −50 to 200° C., more preferably −20 to 120° C., and still more preferably 15 to 100° C., a copolymer having excellent mechanical properties, which is capable of suppressing production of a low-molecular weight polymer to be caused due to partial thermal degradation of the growing terminal anion, can be produced while shortening the polymerization time and keeping the high conversion of 1,3,7-octatriene.

(Polymerization Pressure)

The polymerization of the present invention can be suitably carried out so long as incorporation of a substance which reacts with the growing terminal anion to hinder the polymerization reaction, for example, the air containing oxygen and water, is suppressed.

In the case of using a solvent having a boiling point equal to or lower than the polymerization temperature, the temperature may be controlled by controlling the pressure with an inert gas to control the generation amount of a solvent vapor, or in the case of using a solvent having a boiling point higher than the polymerization temperature, the temperature may be controlled by reducing the pressure in the reaction system by using a vacuum pump to control the generation amount of a vapor of the solvent.

Though the polymerization pressure is not particularly limited, so long as it is 0.01 to 10 MPaG, and more preferably 0.1 to 1 MPaG, not only the use amount of the inert gas is reduced, but also a high pressure-resistant reactor and a pump of venting the inert gas outside the system become unnecessary, and hence, the polymerization can be performed economically advantageously.

(Polymerization Time)

Though the polymerization time is not particularly limited, so long as it is preferably 0.1 to 24 hours, and more preferably 0.5 to 12 hours, a polymer having excellent mechanical properties, which is capable of suppressing production of a low-molecular weight polymer to be caused due to partial thermal degradation of the growing terminal anion, is readily produced.

(Polymerization Terminator and Coupling Agent)

In the production method of a copolymer of the present invention, it is preferred to add a polymerization terminator to the reaction system, thereby terminating the polymerization reaction. Examples of the polymerization terminator include a hydrogen molecule; an oxygen molecule; water; alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, heptanol, cyclohexanol, phenol, benzyl alcohol, o-cresol, m-cresol, p-cresol, ethylene glycol, propylene glycol, butanediol, glycerin, and catechol; halides, such as methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, butyl chloride, butyl bromide, butyl iodide, benzyl chloride, benzyl bromide, benzyl iodide, trimethylsilyl fluoride, trimethylsilyl chloride, trimethylsilyl bromide, trimethylsilyl iodide, triethylsilyl fluoride, triethylsilyl chloride, triethylsilyl bromide, triethylsilyl iodide, tributylsilyl fluoride, tributylsilyl chloride, tributylsilyl bromide, tributylsilyl iodide, triphenylsilyl fluoride, triphenylsilyl chloride, triphenylsilyl bromide, and triphenylsilyl iodide; ketones, such as 2-heptanone, 4-methyl-2-pentanone, cyclopentanone, 2-hexanone, 2-pentanone, cyclohexanone, 3-pentanone, acetophenone, 2-butanone, and acetone; esters, such as methyl acetate, ethyl acetate, and butyl acetate; epoxy compounds, such as ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, and cyclohexane oxide; and silyl hydride compounds, such as methyldichlorosilane, ethyldichlorosilane, propyldichlorosilane, butyldichlorosilane, pentyldichlorosilane, hexyldichlorosilane, heptyldichlorosilane, octyldichlorosilane, nonyldichlorosilane, decyldichlorosilane, phenyldichlorosilane, dimethylchlorosilane, diethylchlorosilane, dipropylchlorosilane, dibutylchlorosilane, dipentylchlorosilane, dihexylchlorosilane, diheptylchlorosilane, dioctylchlorosilane, dinonylchlorosilane, didecylchlorosilane, methylpropylchlorosilane, methylhexylchlorosilane, methylphenylchlorosilane, diphenylchlorosilane, dimethylmethoxysilane, dimethylethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, dimethylphenoxysilane, dimethylbenzyloxysilane, diethylmethoxysilane, diethylethoxysilane, diethylpropoxysilane, diethylbutoxysilane, diethylphenoxysilane, diethylbenzyloxysilane, dipropylmethoxysilane, dipropylethoxysilane, dipropylpropoxysilane, dipropylbutoxysilane, dipropylphenoxysilane, dipropylbenzyloxysilane, dibutylmethoxysilane, dibutylethoxysilane, dibutylpropoxysilane, dibutylbutoxysilane, dibutylphenoxysilane, dibutylbenzyloxysilane, diphenylmethoxysilane, diphenylethoxysilane, diphenylpropoxysilane, diphenylbutoxysilane, diphenylphenoxysilane, diphenylbenzyloxysilane, dimethylsilane, diethylsilane, dipropylsilane, dibutylsilane, diphenylsilane, diphenylmethylsilane, diphenylethylsilane, diphenylpropylsilane, diphenylbutylsilane, trimethylsilane, triethylsilane, tripropylsilane, tributylsilane, triphenylsilane, methylsilane, ethylsilane, propylsilane, butylsilane, phenylsilane, methyldiacetoxysilane, polymethylhydrosiloxane, polyethylhydrosiloxane, polypropylhydrosiloxane, polybutylhydrosiloxane, polypentylhydrosiloxane, polyhexylhydrosiloxane, polyheptylhydrosiloxane, polyoctylhydrosiloxane, polynonylhydrosiloxane, polydecylhydrosiloxane, polyphenylhydrosiloxane, 1,1,3,3-tetramethyldisiloxane, methylhydrocyclosiloxane, ethylhydrocyclosiloxane, propylhydrocyclosiloxane, butylhydrocyclosiloxane, phenylhydrocyclosiloxane, 1,1,3,3-tetramethyldisilazane, 1,1,3,3-tetraethyldisilazane, 1,1,3,3-tetrapropyldisilazane, 1,1,3,3-tetrabutyldisilazane, and 1,1,3,3-tetraphenyldisilazane.

The polymerization terminators may be used alone or may be used in combination of two or more thereof.

The polymerization terminator may be used upon being diluted with a solvent which can be used for the polymerization reaction. Though the use amount of the polymerization terminator is not particularly limited, the matter that the use amount of the polymerization terminator does not become excessive relative to the growing terminal anion is preferred from the viewpoint of recovering and reusing the solvent, and in the case of hydrogenating the copolymer, such is also preferred from the standpoint that the use amount of a hydrogenation catalyst can be reduced.

A conversion of the 1,3,7-octatriene after completion of the anionic polymerization, as determined by gas chromatography, is preferably 80.0% or more, more preferably 88.0% or more, more preferably 90.0% or more, still more preferably 95.0% or more, especially preferably 97.0% or more, and most preferably 98.0% or more, and it is also possible to achieve the conversion of 99.0% or more.

(Hydrogenation Reaction)

From the viewpoints of heat resistance, oxidation resistance, weather resistance, ozone resistance, etc. of the copolymer, at least a part or the whole of carbon-carbon double bonds which the copolymer has may be hydrogenated. Typically, in the production method of the copolymer, to the polymer solution obtained by polymerization termination or the polymer solution optionally diluted with the aforementioned solvent, a hydrogenation catalyst is added to act on hydrogen, a hydride of the copolymer can be produced.

Examples of the hydrogenation catalyst include Raney nickel; a heterogeneous catalyst in which a metal, such as Pt, Pd, Ru, Rh, and Ni, is supported on a carrier, such as carbon, alumina, and diatomaceous earth; a Ziegler-type catalyst composed of a combination of a transition metal compound with an alkylaluminum compound, an alkyllithium compound, or the like; and a metallocene-based catalyst.

A temperature of the hydrogenation reaction is preferably −20 to 250° C., the temperature of which is equal to or higher than the freezing point of the solvent and not higher than the heat decomposition temperature of the copolymer, and it is more preferably 30 to 150° C. from the viewpoint of industrially advantageously producing the hydride of the copolymer. When the hydrogenation reaction temperature is 30° C. or higher, the hydrogenation reaction is advanced, and when it is 150° C. or lower, even if heat decomposition of the hydrogenation catalyst occurs, the hydrogenation reaction can be carried out at a low use amount of the hydrogenation catalyst. The hydrogenation reaction temperature is still more preferably 60 to 100° C. from the viewpoint of reducing the use amount of the hydrogenation catalyst.

The hydrogen can be used in a gaseous form, and its pressure is not particularly limited so long as it is atmospheric pressure or higher; however, it is preferably 0.1 to 20 MPaG from the viewpoint of industrially advantageously producing a hydride of the copolymer. When the pressure is 20 MPaG or lower, even if hydrogen decomposition of the hydrogenation catalyst occurs, the hydrogenation reaction can be carried out at a low use amount of the hydrogenation catalyst. The pressure of hydrogen is still more preferably 0.5 to 10 MPaG from the viewpoint of reducing the use amount of the hydrogenation catalyst.

Though the time required for the hydrogenation reaction can be properly selected according to a condition, it is preferably a range of from 10 minutes to 24 hours since commencement of co-presence of the catalyst from the viewpoint of industrially advantageously producing a hydride of the copolymer.

As for the reaction mixed liquid after completion of the hydrogenation reaction, after being optionally diluted with the aforementioned solvent or concentrated, it is washed with a basic aqueous solution or an acidic aqueous solution, whereby the hydrogenation catalyst can be removed.

As for the polymer solution obtained after the polymerization reaction or the polymer solution obtained after the hydrogenation reaction, after subjecting to a concentration operation, the resultant may be fed into an extruder, thereby isolating the copolymer; it may be brought into contact with steam to remove the solvent and so on, thereby isolating the copolymer; or it may be brought into contact with an inert gas in a heated state to remove the solvent and so on, thereby isolating the copolymer.

(Production Method of High-Purity 1,3,7-Octatriene)

As the production method of 1,3,7-octatriene, a production method of 1,3,7-octatriene having a purity, as determined by gas chromatography, of more than 98.0% is selected; or in the case of 1,3,7-octatriene having a purity of 98.0% or less, it is necessary to purity it to acquire 1,3,7-octatriene having a purity of more than 98.0%.

For example, a method of dimerizing butadiene in the presence of a palladium catalyst, as described in JP 46-24003 B; and deacetylation reaction of 1-acetoxy-2,7-octadiene as described in JP 47-17703 A can be utilized.

On the occasion of producing 1,3,7-octatriene, it is known that 1,3,6-octatriene, 2,4,6-octatriene, or the like, in which the position of a double bond is different, is formed as a by-product. Owing to the matter that a boiling point of such a by-product is close to the boiling point of 1,3,7-octatriene, it is difficult to undergo distillation separation of the by-product from 1,3,7-octatriene, and therefore, it is preferred to adopt the production method of 1,3,7-octatriene, in which the by-product is a few.

In the case where the total content of a peroxide and its decomposition product in 1,3,7-octatriene is more than 0.30 mmol/kg, it is necessary to use 1,3,7-octatriene after reducing the contents of the peroxide and its decomposition product. Though a method of reducing the contents of the peroxide and its decomposition product is not particularly limited, examples thereof include an alumina treatment; and a method in which a compound having a function as an antioxidant and having a higher boiling point than that of 1,3,7-octatriene (for example, 4-tert-butyl catechol, 2,4-di-tert-butylphenol, and triphenyl phosphine) is mixed with 1,3,7-octatriene, followed by performing a distillation treatment. Above all, it is preferred to utilize an alumina treatment.

EXAMPLES

The present invention is hereunder described in more detail by reference to Examples, but it should be construed that the present invention is by no means limited by such Examples.

The production of 1,3,7-octatriene was carried out in an inert gas atmosphere of nitrogen, argon, or the like, without being particularly indicated.

As for all of liquid medicines, those obtained by not only substituting a dissolved gas with an inert gas but also removing an antioxidant and water were used unless otherwise indicated.

As 2,7-octadien-1-ol that is a production raw material of 1,3,7-octatriene, 2,7-octadien-1-ol having a purity of 99.54%, as manufactured by Kuraray Co., Ltd., was used. The foregoing purity was determined according to the following measurement method.

(Measurement Method of Purity of 2,7-Octadien-1-Ol)

The purity of 2,7-octadien-1-ol was determined by means of an analysis of gas chromatography under the following measurement condition. Specifically, a percentage of a “peak area capable of assigning to one 2,7-octadien-1-ol capable of being observed for a retention time of about 17.6 minutes” relative to “sum total of peak areas detected for a retention time of 5 to 20 minutes” was determined, and this was defined as the purity of 2,7-octadien-1-ol. The purity of 2,7-octadien-1-ol was found to be 99.54%.

<Measurement Condition of Gas Chromatography>

Apparatus: “GC-2010 Plus”, manufactured by Shimadzu Corporation

Column: “Rxi-5 ms” (inside diameter: 0.25 mm, length: 30 m, film thickness: 1 μm), manufactured by Restek Corporation

Carrier gas: Helium (113.7 kPaG) was allowed to flow at a flow rate of 1.37 mL/min.

Injection amount of sample: 0.1 μL of the liquid medicine was injected at a split ratio of 100/1.

Detector: FID

Temperature of detector: 280° C.

Temperature of vaporization chamber: 280° C.

Temperature rise condition: After holding at 70° C. for 12 minutes, the temperature was raised to 280° C. at a rate of 20° C./min, followed by holding for 5 minutes.

[Production Example 1] Production of 1,3,7-Octatriene Acetylation Reaction of 2,7-Octadiene-1-ol

A flask having a capacity of 10 L and equipped with a thermometer, a nitrogen feed inlet, a dropping funnel having a capacity of 2 L, and a stirrer was prepared. After purging the interior of the flask with nitrogen, 1,500.8 g (11.892 mol) of 2,7-octadien-1-ol, 1,806.3 g (17.851 mol) of triethylamine, and 72.60 g (0.594 mol) of 4-dimethylaminopyridine were successively charged, and then, the contents were cooled by using a dry ice-acetone bath while stirring at 140 rpm until the liquid temperature reached −40° C., thereby obtaining a mixed liquid. Meanwhile, 1,821.5 g (17.842 mol) of acetic anhydride was charged in the dropping funnel, and the acetic anhydride was added dropwise over 1 hour such that the liquid temperature of the aforementioned mixed liquid was kept at −50 to −30° C.

After completion of the dropwise addition, the reaction was continued for 1 hour, and 700.0 g of distilled water was added to terminate the reaction. The organic phase was recovered and then successively washed with 1 L of a 5% hydrochloric acid two times, 1 L of a saturated sodium hydrogencarbonate aqueous solution two times, 1 L of distilled water one time, and 1 L of a saturated sodium chloride aqueous solution one time. The thus obtained organic phase was dehydrated by the addition of 170 g of anhydrous sodium sulfate, and the anhydrous sodium sulfate was then filtered off, to recover the organic phase.

The recovered organic phase was analyzed by means of gas chromatography under the same condition as in the aforementioned purity analysis of 2,7-octadien-1-ol, to calculate a purity of 1-acetoxy-2,7-octadiene. A percentage of a “sum total of two peak areas capable of being observed for a retention time of about 19.2 minutes and about 19.3 minutes, respectively” relative to a “sum total of peak areas detected for a retention time of 5 to 20 minutes”, namely the purity of 1-acetoxy-2,7-octadiene was found to be 99.51%. 1,851.1 g (yield: 92.5%) of 1-acetoxy-2,7-octadiene having the foregoing purity was acquired.

(Deacetylation Reaction of 1-Acetoxy-2,7-Octadiene)

An interior of a 3-L vacuum distillation apparatus equipped with a Claisen tube distillation head connected with a receiver via a Liebig condenser, a stirrer, and a thermometer was purged with nitrogen, and 1,205.7 g (7.167 mol) of the above-obtained 1-acetoxy-2,7-octadiene, 26.7 g (0.119 mol) of palladium acetate, and 124.8 g (0.4758 mol) of triphenyl phosphine were charged. An internal pressure was controlled to 1.52 to 1.35 kPaA with a vacuum controller while stirring at 200 rpm, and distillation was performed at a rate of 8.0 g/min while heating such that the liquid temperature was 90° C. After removing 41.4 g of an initial distillate, 799.7 g of a subsequently distillated product was recovered.

The recovered distillate was successively washed with 500 mL of a 0.2 mol/L sodium hydroxide aqueous solution three times, 500 mL of distilled water one time, and 500 mL of a saturated sodium chloride aqueous solution one time. The organic phase was dried by the addition of 50 g of anhydrous sodium sulfate, and the anhydrous sodium sulfate was then filtered off, to recover the organic phase.

The recovered organic phase was analyzed by means of gas chromatography under the same condition as in the aforementioned purity analysis of 2,7-octadien-1-ol, and as a result, it was found to be a mixture composed of 46.9% of 1,3,7-octatriene, 23.7% of 1-acetoxy-2,7-octadiene, and 29.4% of 3-acetoxy-1,7-octadiene. 637.0 g of the organic phase was charged in a distillation apparatus having a McMahon packing filled therein and having an inside diameter of 25.4 mm and a height of 240 mm. A distillate was recovered under a condition at 22.1 to 13.0 kPaA such that a reflux ratio was 2 at 79.1 to 60.3° C.

The recovered organic phase was analyzed by means of gas chromatography under the same condition as in the aforementioned purity analysis of 2,7-octadien-1-ol, to calculate a purity of 1,3,7-octatriene. A percentage of a “sum of two peak areas capable of being assigned to 1,3,7-octatriene and observed for a retention time of near 8.7 minutes and 9.0 minutes, respectively” relative to a “sum total of peak areas capable of being assigned to all of the octatrienes and detected for a retention time of 5 to 20 minutes” was calculated according to the following formula 1, and as a result, it was found to be 99.3%. Here, all of the octatrienes mean all of 1,3,7-octatriene and double-bond isomers, such as 1,3,6-octatriene, 2,4,6-octatriene, and 1,4,6-octatriene.

$\begin{matrix} {{{Purity}\mspace{14mu} (\%)} = {\frac{{Peak}\mspace{14mu} {area}\mspace{14mu} {of}\mspace{14mu} 1,3,7\text{-}{octatriene}}{{Sum}\mspace{14mu} {total}\mspace{14mu} {of}\mspace{14mu} {peak}\mspace{14mu} {areas}\mspace{14mu} {of}\mspace{14mu} {all}\mspace{14mu} {of}\mspace{14mu} {octatrienes}} \times 100}} & \left( {{Formula}\mspace{14mu} 1} \right) \end{matrix}$

A total content of the peroxide and its decomposition product in the above-obtained 1,3,7-octatriene was measured according to the following measurement method.

(Measurement Method of Total Content of Peroxide and its Decomposition Product)

After purging a 100-mL three-necked flask equipped with a gas feed port and a condenser with nitrogen, 5.00 g of 1,3,7-octatriene obtained by the aforementioned method was precisely weighed, 20.0 g of isopropyl alcohol, 5.0 g of distilled water, 2.0 g of acetic acid, and 1.6 g of potassium iodide dissolved in 1.5 g of distilled water were added, and then, the contents were heated and stirred for 5 minutes by using an oil bath at 95° C.

After taking out the three-necked flask from the oil bath, the interior of the condenser was washed with a mixed solvent of 6.0 g of isopropyl alcohol and 1.5 g of distilled water, and the washing liquid was mixed with the solution in the three-necked flask. After allowing to stand for cooling to room temperature, 0.005 mmol/mL of a sodium thiosulfate aqueous solution was added dropwise to the three-necked flask, and the total content of a peroxide and its decomposition product was calculated from a volume at which the color was faded from yellow to colorless according to the following formula 2. As a result, the total content of the peroxide and its decomposition product in 1,3,7-octatriene was found to be less than 0.015 mmol/kg.

$\begin{matrix} {{{Total}\mspace{14mu} {content}\mspace{14mu} {of}\mspace{14mu} {perocide}\mspace{14mu} {and}\mspace{14mu} {its}\mspace{14mu} {decomposition}\mspace{14mu} {product}\mspace{14mu} \left( {{mmol}\text{/}{kg}} \right)} = \frac{\; \begin{matrix} {0.005\mspace{14mu} \left( {{mmol}\text{/}{mL}} \right) \times \left\lbrack {{Dropwise}\mspace{14mu} {addition}}\mspace{11mu} \right.} \\ \left. {{amount}\mspace{14mu} {of}\mspace{14mu} {sodium}\mspace{14mu} {thiosulfate}\mspace{14mu} ({mL})} \right\rbrack \end{matrix}}{2 \times 0.005\mspace{14mu} ({kg})}} & \left( {{Formula}\mspace{14mu} 2} \right) \end{matrix}$

There was thus obtained 1,3,7-octatriene having a purity of 99.3% and having a total content of the peroxide and its decomposition product of less than 0.015 mmol/kg. The results are shown in Table 1.

[Production Example 2] Production of 1,3,7-Octatriene

The 1,3,7-octatriene acquired in Production Example 1 was transferred into a glass flask and allowed to stand at room temperature (20 to 25° C.) for 100 hours in an air atmosphere without shading. The purity of the obtained 1,3,7-octatriene and the total content of the peroxide and its decomposition product are shown in Table 1.

[Production Example 3] Production of 1,3,7-Octatriene

The 1,3,7-octatriene acquired in Production Example 1 was transferred into a glass flask and allowed to stand at room temperature (20 to 25° C.) for 200 hours in an air atmosphere without shading. The purity of the obtained 1,3,7-octatriene and the total content of the peroxide and its decomposition product are shown in Table 1.

[Production Example 4] Production of 1,3,7-Octatriene (for Comparative Example 1)

The same operations as in Production Example 1 were followed, except that the distillation rate of 1,3,7-octatriene from the reaction system was changed to 5.0 g/min such that the purity of 1,3,7-octatriene was one as shown in Table 1. The acquired 1,3,7-octatriene was transferred into a glass flask and allowed to stand at room temperature (20 to 25° C.) for 90 hours in an air atmosphere without shading. The purity of the obtained 1,3,7-octatriene and the total content of the peroxide and its decomposition product are shown in Table 1.

[Production Example 5] Production of 1,3,7-Octatriene (for Reference Example 1)

The same operations as in Production Example 1 were followed, except that the distillation rate of 1,3,7-octatriene from the reaction system was changed to 4.0 g/min such that the purity of 1,3,7-octatriene was one as shown in Table 1. The acquired 1,3,7-octatriene was transferred into a glass flask and allowed to stand at room temperature (20 to 25° C.) for 120 hours in an air atmosphere without shading. The purity of the obtained 1,3,7-octatriene and the total content of the peroxide and its decomposition product are shown in Table 1.

[Production Example 6] Production of 1,3,7-Octatriene (for Reference Example 2)

The 1,3,7-octatriene acquired in Production Example 1 was transferred into a glass flask and put into cold storage for 2,000 hours in an air atmosphere. The purity of the obtained 1,3,7-octatriene and the total content of the peroxide and its decomposition product are shown in Table 1.

TABLE 1 Production Example 1,3,7-Octatriene 1 2 3 4 5 6 Purity (%) 99.3 99.2 99.2 97.98 96.72 99.2 Total content of <0.015 0.065 0.26 0.062 0.073 3.37 peroxide and its decomposition product (mmol/kg)

Hereinafter, the production of a copolymer was carried out in an argon gas atmosphere unless otherwise indicated.

As reagents used in each of the Examples, the following were used.

As for isoprene, isoprene (containing a stabilizer), manufactured by Wako Pure Chemical Industries, Ltd., from which moisture and the stabilizer had been removed by using Molecular Sieves 3A and neutral active alumina and further subjected to bubbling with an argon gas to purge the dissolved gas, was used.

As for cyclohexane, cyclohexane (not containing a stabilizer), manufactured by Wako Pure Chemical Industries, Ltd., from which moisture had been removed by using Molecular Sieves 3A and further subjected to bubbling with an argon gas to purge the dissolved gas, was used.

As for sec-butyllithium, a cyclohexane solution of sec-butyllithium, manufactured by Asia Lithium Corporation, a concentration of which had been adjusted with the aforementioned cyclohexane to 1.26 mmol/g, was used.

All of tetrahydrofuran (not containing a stabilizer), diethyl ether (containing a stabilizer), triethylamine, 1,2-diethoxyethane (DEE), and N,N,N′,N′-tetramethylethylenediamine (TMEDA), all of which are manufactured by Wako Pure Chemical Industries, Ltd., and 2,2-di(2-tetrahydrofuryl)propane (DTHFP), manufactured by Tokyo Chemical Industry Co., Ltd., from which moisture and the stabilizer had been removed by using neutral active alumina and further subjected to bubbling with an argon gas to purge the dissolved gas, were used.

As for polystyrene, standard polystyrene (weight average molecular weight (Mw)=1,300, molecular weight distribution (Mw/Mn)=1.06), manufactured by Wako Pure Chemical Industries, Ltd. was used.

In each of the following Examples, with respect to the conversion of each of 1,3,7-octatriene and isoprene, the yield, weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) of the copolymer, and the binding mode were determined according to the following measurement methods, respectively.

(Measurement Method of Conversion)

1.00 g of ethylene glycol dimethyl ether was added to 5.00 g of the polymerization-terminated liquid after completion of the polymerization reaction, and this mixed liquid was analyzed by means of gas chromatography under the following measurement condition.

The conversion (%) of 1,3,7-octatriene was calculated from a “relative area ratio of 1,3,7-octatriene and ethylene glycol dimethyl ether at 0 hour of commencement of polymerization reaction” and a “relative area ratio of unreacted 1,3,7-octatriene and ethylene glycol dimethyl ether after completion of polymerization reaction” according to the following formula 3.

The conversion (%) of isoprene was calculated from a “relative area ratio of isoprene and ethylene glycol dimethyl ether before reaction at 0 hour of commencement of polymerization reaction” and a “relative area ratio of unreacted isoprene and ethylene glycol dimethyl ether after reaction” according to the following formula 4.

<Measurement Condition of Gas Chromatography>

Apparatus: “GC-14B”, manufactured by Shimadzu Corporation

Column: “Rxi-5 ms” (inside diameter: 0.25 mm, length: 30 m, film thickness: 0.25 μm), manufactured by Restek Corporation

Carrier gas: Helium (140.0 kPaG) was allowed to flow at a flow rate of 1.50 mL/min.

Injection amount of sample: 0.1 μL of the liquid medicine was injected at a split ratio of 50/1.

Detector: FID

Temperature of detector: 280° C.

Temperature of vaporization chamber: 280° C.

Temperature rise condition: After holding at 40° C. for 10 minutes, the temperature was raised to 250° C. at a rate of 20° C./min, followed by holding for 5 minutes.

$\begin{matrix} {{{Conversion}\mspace{14mu} (\%)} = {\left( {1 - \frac{\begin{matrix} {{Relative}\mspace{14mu} {area}\mspace{14mu} {ratio}\mspace{14mu} {of}\mspace{14mu} 1,3,7\text{-}{octatriene}} \\ {{after}\mspace{14mu} {completion}\mspace{14mu} {of}} \\ {{polyermerization}\mspace{14mu} {reaction}} \end{matrix}}{\begin{matrix} {{Relative}\mspace{14mu} {area}\mspace{14mu} {ratio}\mspace{14mu} {of}\mspace{14mu} 1,3,7\text{-}{octatriene}} \\ {{at}\mspace{14mu} 0\mspace{14mu} {hour}\mspace{14mu} {of}\mspace{11mu} {commencement}} \\ {\; {{of}\mspace{14mu} {polyermerization}\mspace{14mu} {reaction}}} \end{matrix}}} \right) \times 100}} & {\left( {{Formula}\mspace{14mu} 3} \right)\;} \\ {{{Conversion}\mspace{14mu} (\%)} = {\left( {1 - \frac{\begin{matrix} {{Relative}\mspace{14mu} {area}\mspace{14mu} {ratio}\mspace{14mu} {of}\mspace{14mu} {isoprene}} \\ {{after}\mspace{14mu} {completion}\mspace{14mu} {of}\mspace{14mu} {polyermerization}\mspace{14mu} {reaction}} \end{matrix}}{\begin{matrix} {{Relative}\mspace{14mu} {area}\mspace{14mu} {ratio}\mspace{14mu} {of}\mspace{14mu} {isoprene}} \\ {{at}\mspace{14mu} 0\mspace{14mu} {hour}\mspace{14mu} {of}\mspace{11mu} {commencement}} \\ {{of}\mspace{14mu} {polyermerization}\mspace{14mu} {reaction}} \end{matrix}}} \right) \times 100}} & \left( {{Formula}\mspace{14mu} 4} \right) \end{matrix}$

(Measurement Method of Yield of Copolymer)

The yield of the obtained copolymer was determined on a basis of the charged amount of the raw material monomers according to the following formula 5.

$\begin{matrix} {{{Yield}\mspace{14mu} (\%)} = {\frac{{Mass}\mspace{14mu} {of}\mspace{14mu} {obtained}\mspace{14mu} {copolymer}\mspace{14mu} (g)}{\begin{matrix} {{Mass}\mspace{14mu} {of}\mspace{14mu} {raw}\mspace{14mu} {material}\mspace{14mu} {monomers}} \\ {{used}\mspace{14mu} {for}\mspace{14mu} {polyermerization}\mspace{14mu} {reaction}\mspace{14mu} (g)} \end{matrix}} \times 100}} & \left( {{Formula}\mspace{14mu} 5} \right) \end{matrix}$

(Measurement Method of Weight Average Molecular Weight (Mw) and Molecular Weight Distribution (Mw/Mn))

To 0.10 g of the obtained copolymer, 60.0 g of tetrahydrofuran was added to prepare a uniform solution; this solution was analyzed by means of gel permeation chromatography under the following measurement condition, to determine the weight average molecular weight (Mw) and the number average molecular weight (Mn) as expressed in terms of standard polystyrene; and the molecular weight distribution (Mw/Mn) was calculated.

<Measurement Condition of Gel Permeation Chromatography>

Apparatus: “HLC-8320GPC EcoSEC”, manufactured by Tosoh Corp oration

Column; Two of “TSKgel SuperMultipore HZ-M” (inside diameter: 4.6 mm, length: 150 mm), manufactured by Tosoh Corporation were connected in series and used.

Eluent: Tetrahydrofuran was allowed to flow at a flow rate of 0.35 mL/min.

Injection amount of sample: 10 μL

Detector: RI

Temperature of detector: 40° C.

(Binding Mode)

To 150 mg of the obtained copolymer, 1.00 g of deuterochloroform was added to prepare a uniform solution, and this solution was subjected to ¹³C-NMR measurement under the following measurement condition.

<¹³C-NMR Measurement Condition>

Apparatus: “JNM-LA500”, manufactured by JEOL Ltd.

Reference material: Tetramethylsilane

Measurement temperature: 25° C.

Cumulative number: 15,000 times

As a result of the ¹³C-NMR measurement, a “peak capable of being assigned to one carbon atom of the 1,2-bond” of 1,3,7-octatriene was observed at 6138.1 to 138.6 ppm; “peaks capable of being assigned to one carbon atom of the 1,4-bond and one carbon atom of the 3,4-bond” were observed at 6138.8 to 139.4 ppm; and a “peak capable of being assigned to one carbon atom of the 3,4-bond” was observed at 6140.9 to 141.6 ppm. A value obtained by subtracting a peak area at 6140.9 to 141.6 ppm from a peak area at 6138.8 to 139.4 ppm was defined as a peak area corresponding to one carbon atom of the 1,4-bond.

A “peak capable of being assigned to one carbon atom of the 1,2-bond” of isoprene was observed at 6140.5 to 141.0 ppm; a “peak capable of being assigned to one carbon atom of the 1,4-bond” was observed at 6122.0 to 126.9 ppm; and a “peak capable of being assigned to one carbon atom of the 3,4-bond” was observed at 6110.2 to 112.2 ppm.

A ratio of each of the 1,2-bond, the 1,4-bond, and the 3,4-bond derived from 1,3,7-octatriene and a ratio of each of the 1,2-bond, the 1,4-bond, and the 3,4-bond derived from isoprene, each of which was contained in the copolymer, were determined according to the following formulae 6 to 8, respectively.

$\begin{matrix} {{{Ratio}\mspace{14mu} {of}\mspace{14mu} {the}\mspace{14mu} 1,2\text{-}{bond}\mspace{14mu} (\%)} = \frac{{Peak}\mspace{14mu} {area}\mspace{14mu} {assigned}\mspace{14mu} {to}\mspace{14mu} {the}\mspace{14mu} 1,2\text{-}{bond}}{\begin{matrix} {{Sum}\mspace{14mu} {total}\mspace{14mu} {of}\mspace{14mu} {peak}\mspace{14mu} {areas}\mspace{14mu} {assigned}\mspace{14mu} {to}} \\ {{{the}\mspace{14mu} 1,2\text{-}{bond}},{{the}\mspace{14mu} 1,4\text{-}{bond}},{{and}\mspace{14mu} {the}\mspace{14mu} 3,4\text{-}{bond}}} \end{matrix}}} & \left( {{Formula}\mspace{14mu} 6} \right) \\ {{{Ratio}\mspace{14mu} {of}\mspace{14mu} {the}\mspace{14mu} 1,4\text{-}{bond}\mspace{14mu} (\%)} = \frac{{Peak}\mspace{14mu} {area}\mspace{14mu} {assigned}\mspace{14mu} {to}\mspace{14mu} {the}\mspace{14mu} 1,4\text{-}{bond}}{\begin{matrix} {{Sum}\mspace{14mu} {total}\mspace{14mu} {of}\mspace{14mu} {peak}\mspace{14mu} {areas}\mspace{14mu} {assigned}\mspace{14mu} {to}} \\ {{{the}\mspace{14mu} 1,2\text{-}{bond}},{{the}\mspace{14mu} 1,4\text{-}{bond}},{{and}\mspace{14mu} {the}\mspace{14mu} 3,4\text{-}{bond}}} \end{matrix}}} & \left( {{Formula}\mspace{14mu} 7} \right) \\ {{{Ratio}\mspace{14mu} {of}\mspace{14mu} {the}\mspace{14mu} 3,4\text{-}{bond}\mspace{14mu} (\%)} = \frac{{Peak}\mspace{14mu} {area}\mspace{14mu} {assigned}\mspace{14mu} {to}\mspace{14mu} {the}\mspace{14mu} 3,4\text{-}{bond}}{\begin{matrix} {{Sum}\mspace{14mu} {total}\mspace{14mu} {of}\mspace{14mu} {peak}\mspace{14mu} {areas}\mspace{14mu} {assigned}\mspace{14mu} {to}} \\ {{{the}\mspace{14mu} 1,2\text{-}{bond}},{{the}\mspace{14mu} 1,4\text{-}{bond}},{{and}\mspace{14mu} {the}\mspace{14mu} 3,4\text{-}{bond}}} \end{matrix}}} & \left( {{Formula}\mspace{14mu} 8} \right) \end{matrix}$

[Example 1] Production of Copolymer

The interior of an SUS316 (registered trademark)-made autoclave having a capacity of 1 L and equipped with a thermometer, an electric heater, an electromagnetic induction agitator, a chemical liquid charging port, and a sampling port was purged with argon, and then, 232.0 g of cyclohexane was charged. Subsequently, the internal pressure was regulated with argon to 0.1 MPaG, and then, the temperature was raised to 50° C. over 30 minutes while stirring at 250 rpm. 0.278 g (3.85 mmol) of tetrahydrofuran (THF) was charged in an argon gas stream, subsequently, 0.611 g of a cyclohexane solution containing 1.260 mmol/g of sec-butyllithium (0.77 mmol in terms of sec-butyllithium) was charged, and then, the internal pressure was regulated with argon to 0.3 MPaG.

Meanwhile, 86.22 g (0.797 mol) of 1,3,7-octatriene obtained in Production Example 1 and 69.07 g (1.014 mol) of isoprene were mixed, and then, the mixture was fed into the autoclave having sec-butyllithium resided therein over 1 hour. The point of time when the charging was commenced was defined as 0 hour of commencement of the polymerization reaction, and the reaction was performed for 6.5 hours while controlling the liquid temperature to 50° C.

Thereafter, 0.32 g of a cyclohexane solution containing 2.50 mmol/g of ethanol (0.80 mmol in terms of ethanol) was added, thereby terminating the polymerization reaction.

Subsequently, the whole amount of the obtained polymerization-terminated liquid was transferred into a 1-L eggplant type flask, and almost of all of the solvent was distilled off while heating at 40° C. and at 100 kPaA by using a rotatory evaporator. Furthermore, the aforementioned eggplant type flask was transferred into a vacuum dryer and dried for 12 hours while heating at 25° C. and at 0.1 kPaA, thereby acquiring 153.1 g of a copolymer in a liquid state. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 2.

Examples 2 to 14

Copolymers were obtained by performing the polymerization reaction in the same manner as in Example 1, except that each of the reagents and the use amount thereof and the reaction condition were changed to those as shown in Table 2. The polymerization time was one described in Table 2. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 2.

Examples 15 and 16

Copolymers were obtained by performing the polymerization reaction in the same manner as in Example 1, except for using the 1,3,7-octatriene obtained in Production Example 2 in places of the 1,3,7-octatriene obtained in Production Example 1 and further changing each of the reagents and the use amount thereof and the reaction condition as shown in Table 3. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Example 17

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 1, except for using the 1,3,7-octatriene obtained in Production Example 3 in places of the 1,3,7-octatriene obtained in Production Example 1 and further changing each of the reagents and the use amount thereof and the reaction condition as shown in Table 3. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Example 18

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 2, except for changing the use amount of tetrahydrofuran (THF) from 0.689 g (9.55 mmol) to 27.542 g (382 mmol). The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Example 19

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 12, except for changing the use amount of N,N,N′,N′-tetramethylethylenediamine (TMEDA) from 0.182 g (1.57 mmol) to 0.728 g (6.26 mmol). The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Examples 20 and 21

Copolymers were obtained by performing the polymerization reaction in the same manner as in Example 2, except for changing the polymerization temperature and the polymerization time as shown in Table 3. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Examples 22 and 23

Copolymers were obtained by performing the polymerization reaction in the same manner as in Example 1, except that the use amount of each of reagents was changed to one as shown in Table 3, thereby regulating a solid content concentration of the reaction liquid after completion of the anionic polymerization to 20% by mass and 61% by mass, respectively. The polymerization time was 1 hour and 2 hours, respectively. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Example 24(1)

A copolymer having a living anionic active species at a molecular end thereof was obtained by performing the reaction for 5 hours in the same manner as in Example 1, except that the use amount of each of reagents was changed to one as shown in Table 3, thereby regulating a solid content concentration of the reaction liquid after completion of the anionic polymerization to 30% by mass. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Example 24(2)

To the autoclave containing the copolymer having a living anionic active species at a molecular end thereof as obtained in Example 24(1), 52.45 g (0.485 mol) of the 1,3,7-octatriene obtained in Production Example 1 and 41.99 g (0.616 mol) of isoprene were added, and the contents were allowed to react with each other for 6 hours, thereby obtaining a copolymer. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Comparative Example 1

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 17, except that the 1,3,7-octatriene obtained in Production Example 4 was used in place of the 1,3,7-octatriene obtained in Production Example 1. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Reference Example 1

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 17, except that the 1,3,7-octatriene obtained in Production Example 5 was used in place of the 1,3,7-octatriene obtained in Production Example 1. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

Reference Example 2

A copolymer was obtained by performing the polymerization reaction in the same manner as in Example 17, except that the 1,3,7-octatriene obtained in Production Example 6 was used in place of the 1,3,7-octatriene obtained in Production Example 1. The polymerization time was one described in Table 3. The use amount of each of the reagents, the reaction condition, and the reaction results are shown in Table 3.

TABLE 2 Example 1 2 3 4 5 6 7 Reaction condition Purity of 1,3,7-octatriene (%) 99.3 99.3 99.3 99.3 99.3 99.3 99.3 Total content of peroxide and its <0.015 <0.015 <0.015 <0.015 <0.015 <0.015 <0.015 decomposition product (mmol/kg) Use amount of 1,3,7-octatriene (mol) 0.797 0.797 0.797 1.389 1.389 1.389 0.113 Use amount of isoprene (mol) 1.014 1.014 1.014 0.0716 0.0716 0.0716 2.101 Total use amount of raw material monomers 1.811 1.811 1.811 1.4606 1.4606 1.4606 2.214 (mol) Content α of 1,3,7-octatriene (mol %) 44.01 44.01 44.01 95.10 95.10 95.10 5.10 Use amount of 1,3,7-octatriene (g) 86.22 86.22 86.22 150.26 150.26 150.26 12.22 Use amount of isoprene (g) 69.07 69.07 69.07 4.88 4.88 4.88 143.12 Use amount of cyclohexane (g) 232.0 232.0 210.2 232.0 232.0 224.8 232.0 Solid content concentration after completion 40 40 40 40 40 40 40 of polymerization reaction (mass %) Use amount of anionic polymerization initiator 0.77 1.91 19.74 1.34 2.81 6.83 1.00 (mmol) (Total amount of raw material monomers)/ 2352 948 92 1090 520 214 2214 (Anionic polymerization initiator) (molar ratio) Kind of Lewis base THF THF THF THF THF THF THF Use amount of Lewis base (g) 0.278 0.689 7.117 0.483 1.013 2.463 0.361 Use amount of Lewis base (mmol) 3.85 9.55 98.70 6.70 14.05 34.15 5.00 (Lewis base)/(Anionic polymerization initiator) 5 5 5 5 5 5 5 (molar ratio) Polymerization temperature (° C.) 50 50 50 50 50 50 50 Polymerization time (hr) 6.5 4 2.5 5 2 0.5 6 Reaction results Conversion of 1,3,7-octatriene (%) 96.6 97.9 99.0 99.1 99.1 99.3 95.2 Conversion of isoprene (%) >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 Weight average molecular weight (Mw) of 298,890 132,040 21,990 171,540 95,610 51,710 297,060 copolymer Molecular weight distribution (Mw/Mn) of 1.78 1.32 1.21 1.65 1.32 1.21 1.10 copolymer Numerical value determined according to the 2.14 1.61 1.26 1.74 1.50 1.36 2.13 formula (i) Rate of 1,2-bond of octatriene (%) 44.5 44.8 49.4 48.2 — — 41.8 Rate of 1,4-bond of octatriene (%) 55.5 55.2 48.0 48.8 — — 58.2 Rate of 3,4-bond of octatriene (%) Undetected Undetected 2.6 3.1 — — Undetected Rate of 1,2-bond of isoprene (%) Undetected Undetected 2.2 Undetected — — Undetected Rate of 1,4-bond of isoprene (%) 71.6 59.1 29.7 56.0 — — 71.4 Rate of 3.4-bond of isoprene (%) 28.4 40.9 68.1 44.0 — — 28.6 Example 8 9 10 11 12 13 14 Reaction condition Purity of 1,3,7-octatriene (%) 99.3 99.3 99.3 99.3 99.3 99.3 99.3 Total content of peroxide and its <0.015 <0.015 <0.015 <0.015 <0.015 <0.015 <0.015 decomposition product (mmol/kg) Use amount of 1,3,7-octatriene (mol) 0.113 0.113 1.389 1.389 1.389 1.389 1.389 Use amount of isoprene (mol) 2.101 2.101 0.0716 0.0716 0.0716 0.0716 0.0716 Total use amount of raw material monomers 2.214 2.214 1.4606 1.4606 1.4606 1.4606 1.4606 (mol) Content α of 1,3,7-octatriene (mol %) 5.10 5.10 95.10 95.10 95.10 95.10 95.10 Use amount of 1,3,7-octatriene (g) 12.22 12.22 150.26 150.26 150.26 150.26 150.26 Use amount of isoprene (g) 143.12 143.12 4.88 4.88 4.88 4.88 4.88 Use amount of cyclohexane (g) 232.0 232.0 232.0 232.0 232.0 232.0 232.0 Solid content concentration after completion 40 40 40 40 40 40 40 of polymerization reaction (mass %) Use amount of anionic polymerization initiator 2.69 4.96 3.13 3.13 3.13 3.13 3.13 (mmol) (Total amount of raw material monomers)/ 823 446 467 467 467 467 467 (Anionic polymerization initiator) (molar ratio) Kind of Lewis base THF THF Et₂O NEt₃ TMEDA DEE DTHFP Use amount of Lewis base (g) 0.970 1.788 1.160 1.584 0.182 0.174 0.260 Use amount of Lewis base (mmol) 13.45 24.80 15.65 15.65 1.57 1.47 1.41 (Lewis base)/(Anionic polymerization initiator) 5 5 5 5 0.5 0.47 0.45 (molar ratio) Polymerization temperature (° C.) 50 50 50 50 50 50 50 Polymerization time (hr) 2 1 7 6 5 4 6 Reaction results Conversion of 1,3,7-octatriene (%) 98.5 99.7 99.3 99.2 99.4 98.8 99.2 Conversion of isoprene (%) >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 Weight average molecular weight (Mw) of 105,430 45,360 75,340 72,080 88,020 73,550 78,660 copolymer Molecular weight distribution (Mw/Mn) of 1.09 1.05 1.33 1.34 1.49 1.39 1.43 copolymer Numerical value determined according to the 1.53 1.34 1.43 1.42 1.47 1.43 1.44 formula (i) Rate of 1,2-bond of octatriene (%) — 47.3 — — 47.9 — — Rate of 1,4-bond of octatriene (%) — 52.7 — — 44.8 — — Rate of 3,4-bond of octatriene (%) — Undetected — — 7.3 — — Rate of 1,2-bond of isoprene (%) — Undetected — — 7.5 — — Rate of 1,4-bond of isoprene (%) — 45.0 — — 69.0 — — Rate of 3.4-bond of isoprene (%) — 55.0 — — 23.5 — —

TABLE 3 Example 15 16 17 18 19 20 21 Reaction condition Purity of 1,3,7-octatriene (%) 99.2 99.2 99.2 99.3 99.3 99.3 99.3 Total content of peroxide and its 0.065 0.065 0.26 <0.015 <0.015 <0.015 <0.015 decomposition product (mmol/kg) Use amount of 1,3,7-octatriene (mol) 0.797 1.389 1.389 0.797 1.389 0.797 0.797 Use amount of isoprene (mol) 1.014 0.0716 0.0716 1.014 0.0716 1.014 1.014 Total use amount of raw material 1.811 1.4606 1.4606 1.811 1.4606 1.811 1.811 monomers (mol) Content α of 1,3,7-octatriene 44.01 95.10 95.10 44.01 95.10 44.01 44.01 (mol %) Use amount of 1,3,7-octatriene (g) 86.22 150.26 150.26 86.22 150.26 86.22 86.22 Use amount of isoprene (g) 69.07 4.88 4.88 69.07 4.88 69.07 69.07 Use amount of cyclohexane (g) 232.0 232.0 232.0 203.9 232.0 232.0 232.0 Solid content concentration after 40 40 40 40 40 40 40 completion of polymerization reaction (mass %) Use amount of anionic polymerization 1.91 3.00 3.00 1.91 3.13 1.91 1.91 initiator (mmol) (Total amount of raw material monomers)/ 948 487 487 948 467 948 948 (Anionic polymerization initiator) (molar ratio) Kind of Lewis base — — TMEDA THF TMEDA THF THF Use amount of Lewis base (g) — — 0.349 27.542 0.728 0.689 0.689 Use amount of Lewis base (mmol) — — 3.00 382.00 6.26 9.55 9.55 (Lewis base)/(Anionic polymerization — — 1 200 2 5 5 initiator) (molar ratio) Polymerization temperature (° C.) 50 50 50 50 50 30 85 Polymerization time (hr) 8 8 10 7 8 12 1 Reaction time after addition of 1,3,7- octatriene and isoprene (hr) Reaction results Conversion of 1,3,7-octatriene (%) 81.4 82.3 90.3 82.9 88.8 98.2 99.8 Conversion of isoprene (%) >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 Weight average molecular weight (Mw) 100,730 50,490 54,970 122,790 67,100 107,890 178,770 of copolymer Molecular weight distribution (Mw/Mn) 1.08 1.18 1.25 1.87 1.67 1.24 1.76 of copolymer Numerical value determined according 1.51 1.35 1.37 1.58 1.41 1.54 1.76 to the formula (i) Rate of 1,2-bond of octatriene (%) 45.9 — — 46.5 — 44.3 47.4 Rate of 1,4-bond of octatriene (%) 53.4 — — 49.0 — 54.7 50.7 Rate of 3,4-bond of octatriene (%) 0.7 — — 4.5 — 1.0 1.9 Rate of 1,2-bond of isoprene (%) 0.0 — — 1.8 — 2.0 0.6 Rate of 1,4-bond of isoprene (%) 93.2 — — 13.5 — 40.0 62.6 Rate of 3.4-bond of isoprene (%) 6.8 — — 84.7 — 58.0 36.8 Comparative Example Example Reference Example 22 23 24(1) 24(2) 1 1 2 Reaction condition Purity of 1,3,7-octatriene (%) 99.3 99.3 99.3 99.3 97.98 96.72 99.2 Total content of peroxide and its <0.015 <0.015 <0.015 <0.015 0.062 0.073 3.37 decomposition product (mmol/kg) Use amount of 1,3,7-octatriene (mol) 0.517 1.64 0.512 0.997 1.389 1.389 1.389 Use amount of isoprene (mol) 0.316 1.003 0.652 1.268 0.0716 0.0716 0.0716 Total use amount of raw material 0.833 2.643 1.164 2.265 1.4606 1.4606 1.4606 monomers (mol) Content α of 1,3,7-octatriene 62.04 62.04 44.01 44.01 95.10 95.10 95.10 (mol %) Use amount of 1,3,7-octatriene (g) 55.89 177.42 55.41 107.86 150.26 150.26 150.26 Use amount of isoprene (g) 21.53 68.34 44.39 86.38 4.88 4.88 4.88 Use amount of cyclohexane (g) 310.0 146.0 232.0 232.0 232.0 232.0 232.0 Solid content concentration after 20 61 30 45 40 40 40 completion of polymerization reaction (mass %) Use amount of anionic polymerization 4.45 14.00 2.39 2.39 3.00 3.00 3.00 initiator (mmol) (Total amount of raw material monomers)/ 187 189 487 948 487 487 487 (Anionic polymerization initiator) (molar ratio) Kind of Lewis base THF THF THF THF TMEDA TMEDA TMEDA Use amount of Lewis base (g) 1.604 0.068 0.862 0.862 0.349 0.349 0.349 Use amount of Lewis base (mmol) 22.25 0.94 11.95 11.95 3.00 3.00 3.00 (Lewis base)/(Anionic polymerization 5 5 5 5 1 1 1 initiator) (molar ratio) Polymerization temperature (° C.) 50 50 50 50 50 50 50 Polymerization time (hr) 1 2 5 8 8 3 Reaction time after addition of 1,3,7- 6 octatriene and isoprene (hr) Reaction results Conversion of 1,3,7-octatriene (%) 98.6 >99.9 99.0 98.2 94.8 84.6 24.9 Conversion of isoprene (%) >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 >99.9 Weight average molecular weight (Mw) 23,760 39,530 67,700 152,200 57,220 55,100 30,330 of copolymer Molecular weight distribution (Mw/Mn) 1.12 1.24 1.30 1.50 2.07 2.03 1.99 of copolymer Numerical value determined according 1.27 1.32 1.41 1.67 1.38 1.37 1.29 to the formula (i) Rate of 1,2-bond of octatriene (%) 49.3 47.4 45 44.8 — — — Rate of 1,4-bond of octatriene (%) 48.4 49.7 55 55.2 — — — Rate of 3,4-bond of octatriene (%) 2.3 2.9 Undetected Undetected — — — Rate of 1,2-bond of isoprene (%) 1.2 2.5 Undetected Undetected — — — Rate of 1,4-bond of isoprene (%) 39.2 26.6 47 53.0 — — — Rate of 3.4-bond of isoprene (%) 59.6 70.9 53 47.0 — — —

The Lewis bases described in Tables 2 and 3 are as follows.

THF: Tetrahydrofuran

Et₂O: Diethyl ether

NEt₃: Triethylamine

TMEDA: N,N,N′,N′-Tetramethylethylenediamine

DEE: 1,2-Diethoxyethane

DTHFP: 2,2-Di(2-tetrahydrofuryl)propane

From Tables 2 and 3, the copolymers obtained by subjecting 1,3,7-octatriene having not only a purity of more than 98.0% but also a total content of a peroxide and its decomposition product of 0.30 mmol/kg or less and isoprene to anionic polymerization (see the Examples) are narrower in the molecular weight distribution (Mw/Mn) than the copolymers obtained by subjecting 1,3,7-octatriene having a purity of 98.0% or less or having a total content of a peroxide and its decomposition product of more than 0.30 mmol/kg and isoprene to anionic polymerization (see the Comparative Example or Reference Examples). In this way, nevertheless a difference in each of the purity and the total content of a peroxide and its decomposition product was not large, as for the copolymers obtained in the Examples, the molecular weight distribution (Mw/Mn) could be made narrow. In addition, in the Examples, there is a tendency that a high conversion can be achieved for a short time, as compared with the Comparative Example or Reference Examples. Furthermore, as for the copolymers obtained in the Examples, those having a large weight average molecular weight (Mw) can be obtained, too.

With respect to the copolymers obtained in Examples 2, 3, 5 to 11, 13 to 17, 20, 22, and 23, the molecular weight distribution (Mw/Mn) is less than 1.44.

The copolymers obtained in Examples 1 to 11, 13 to 17, 20, 22, 23, 24(1), and 24(2) are a copolymer having a molecular weight distribution (Mw/Mn) smaller than the value determined according the formula (i).

The copolymers obtained in Examples 1 to 6, 10 to 23, 24(1), and 24(2) are a copolymer in which not only the content of the structural unit derived from 1,3,7-octatriene is more than 21.0 mol % relative to the total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, but also the molecular weight distribution (Mw/Mn) is less than 2.06.

In addition, from the results of Examples 1 to 14, 17 to 23, 24(1), and 24(2) using the Lewis base and the results of Example 15 to 16 not using the Lewis base, it is noted that in the case of using the Lewis base, there is a tendency that the high conversion can be achieved, and in particular, it is easy to achieve the high conversion for a short time.

Furthermore, as demonstrated in Examples 22 and 23, even by performing the polymerization reaction by regulating the solid content concentration after completion of the anionic polymerization to 20% by mass or 61% by mass, the copolymers of 1,3,7-octatriene having a narrow molecular weight distribution (Mw/Mn) could be obtained.

[Example 25] Production of Hydride (Production of Copolymer as Precursor of Hydrogenated Polymer)

The same operations as in Example 1 were followed to acquire a cyclohexane solution containing a copolymer formed from 1,3,7-octatriene and isoprene.

(Preparation of Hydrogenation Catalyst)

In a 1-L three-necked flask having been purged with nitrogen, 25.1 g of a 2-ethylhexanoic acid solution of nickel(II) bis(2-ethylhexanoate) (containing 53.5 mmol of a nickel atom) (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 284.4 g of cyclohexane, 31.8 g (160.3 mmol) of triisobutylaluminum (manufactured by Nippon Aluminum Alkyls, Ltd.) was then added over 10 minutes, and the contents were stirred for 30 minutes, to prepare a hydrogenation catalyst. This hydrogenation catalyst was used for the following hydrogenation reaction.

(Hydrogenation Reaction)

The autoclave in which the aforementioned copolymer had been produced was cooled to 25° C., 290 g of the polymer solution was then extracted, and subsequently, 290 g of cyclohexane was introduced. The interior of the autoclave was purged with a hydrogen gas and further pressurized with a hydrogen gas to 0.2 MPaG, and subsequently, the autoclave was heated such that the liquid temperature reached 75° C. Thereafter, 0.49 g of the aforementioned hydrogenation catalyst (corresponding to 114.55 ppm by mass in terms of a nickel metal relative to the copolymer) was added, and subsequently, the contents were allowed to react for 2 hours by regulating the internal pressure with a hydrogen gas to 0.98 MPaG.

Thereafter, 0.49 g of the aforementioned hydrogenation catalyst (corresponding to 114.55 ppm by mass in terms of a nickel metal relative to the copolymer) was added three times at intervals of 2 hours. The use amount of the hydrogenation catalyst was 458.2 ppm by mass in total as expressed in terms of a nickel metal relative to the copolymer, and the time of the hydrogenation reaction was 8 hours after first introduction of the hydrogenation catalyst.

First of all, to 150 mg of the copolymer before hydrogenation, 10 mg of standard polystyrene was added, and then, 1.00 g of deuterochloroform was added, thereby preparing a uniform solution. This solution was subjected to ¹H-NMR measurement under the following measurement condition. In addition, to 150 mg of the hydride of the copolymer, 10 mg of standard polystyrene was added, and then, 1.00 g of deuterochloroform was added, thereby preparing a uniform solution. This solution was also subjected to ¹H-NMR measurement under the following measurement condition.

As a result of the ¹H-NMR measurement under the following condition, as the binding modes constituted of octatrienes as a structural unit, “peaks capable of being assigned to four hydrogen atoms of the 1,2-bond, four hydrogen atoms of the 1,4-bond, and four hydrogen atoms of the 3,4-bond” were observed at δ4.8 to 5.5 ppm; a “peak capable of being assigned to one hydrogen atom of the 3,4-bond” was observed at δ5.5 to 5.7 ppm; and “peaks capable of being assigned to one hydrogen atom of the 1,2-bond, one hydrogen atom of the 1,4-bond, and one hydrogen atom of the 3,4-bond” were observed at δ5.7 to 5.9 ppm. As the binding modes constituted of isoprene as a structural unit, “peaks capable of being assigned to two hydrogen atoms of the 3,4-bond” were observed at δ4.6 to 4.8 ppm; a “peak capable of being assigned to one hydrogen atom of the 1,4-bond” was observed at δ5.1 to 5.3 ppm; and a “peak capable of being assigned to one hydrogen atom of the 1,2-bond” was observed at δ5.7 to 6.0 ppm. In addition, “peaks capable of being assigned to five hydrogen atoms of the aromatic ring of polystyrene” were observed at 66.2 to 7.5 ppm.

From the molar number of the double bonds of non-hydrogenated 1,3,7-octatriene and isoprene relative to the total molar number of styrene in the copolymer before the hydrogenation and the molar number of the double bonds of non-hydrogenated 1,3,7-octatriene and isoprene relative to the total molar number of styrene in the copolymer after the hydrogenation treatment, a hydrogenation rate as a ratio of the material hydrogenated with the double bonds derived from 1,3,7-octatriene and isoprene was calculated to be 98.6%.

<¹H-NMR Measurement Condition>

Apparatus: “JNM-LA500”, manufactured by JEOL Ltd.

Reference material: Tetramethylsilane

Measurement temperature: 25° C.

Cumulative number: 254 times

INDUSTRIAL APPLICABILITY

The copolymer of the present invention is useful as a raw material of adhesives and lubricating agents as well as a functional material such as a lubricant for various rubbers and a modifier. 

1: A copolymer comprising a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) of less than 1.44. 2: A copolymer comprising a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a molecular weight distribution (Mw/Mn) smaller than a value determined according to the following formula (i): 3.1569×10⁻⁶×[Weight average molecular weight (Mw)]+1.1945  (i). 3: A copolymer comprising a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having not only a content of the structural unit derived from 1,3,7-octatriene of more than 21.0 mol % relative to a total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, but also a molecular weight distribution (Mw/Mn) thereof of less than 2.06. 4: The copolymer according to claim 1, having a weight average molecular weight (Mw) of 5,000 to 500,000. 5: The copolymer according to claim 1, having a weight average molecular weight (Mw) of 20,000 to 500,000. 6: The copolymer according to claim 1, having a weight average molecular weight (Mw) of 50,000 to 500,000. 7: The copolymer according to claim 1, having a weight average molecular weight (Mw) of 210,000 to 500,000. 8: The copolymer according to claim 1, not having a living anionic active species at a molecular end thereof. 9: The copolymer according to claim 1, having a living anionic active species at a molecular end thereof. 10: A copolymer comprising a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the copolymer having a living anionic active species at a molecular end thereof and having a molecular weight distribution (Mw/Mn) of 2.50 or less. 11: The copolymer according to claim 10, having a weight average molecular weight (Mw) of 5,000 to 500,000. 12: The copolymer according to claim 1, further comprising a structural unit derived from a conjugated diene compound having 6 or more carbon atoms. 13: The copolymer according to claim 12, wherein the conjugated diene compound having 6 or more carbon atoms is at least one selected from the group consisting of 2,3-dimethyl-1,3-butadiene, 4,5-diethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2-benzyl-1,3-butadiene, 2-p-toluyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-diethyl-1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-diethyl-1,3-heptadiene, 3-butyl-1,3-octadiene, 2,3-dimethyl-1,3-octadiene, 4,5-diethyl-1,3-octadiene, 1,3-cyclohexadiene, and myrcene. 14: A hydride of the copolymer according to claim
 1. 15: A method of producing a copolymer containing a structural unit derived from 1,3,7-octatriene and a structural unit derived from isoprene, the method comprising subjecting 1,3,7-octatriene having a purity, as determined by gas chromatography, of more than 98.0% and isoprene to anionic polymerization, wherein impurities which may be contained in the 1,3,7-octatriene include at least one selected from the group consisting of a peroxide and its decomposition product, and a total content of the peroxide and its decomposition product in the 1,3,7-octatriene is 0.30 mmol/kg or less; and the copolymer satisfies at least one of the following conditions I to III: Condition I: a molecular weight distribution (Mw/Mn) is less than 1.44; Condition II: a molecular weight distribution (Mw/Mn) is smaller than a value determined according to the following formula (i): 3.1569×10⁻⁶×[Weight average molecular weight (Mw)]+1.1945  (i); and Condition III: not only a content of the structural unit derived from 1,3,7-octatriene is more than 21.0 mol % relative to a total amount of the structural unit derived from 1,3,7-octatriene and the structural unit derived from isoprene, but also a molecular weight distribution (Mw/Mn) thereof is less than 2.06. 16: The method of claim 15, wherein the 1,3,7-octatriene has a purity, as determined by gas chromatography, of 98.5% or more. 17: The method of claim 15, wherein the anionic polymerization is carried out in the presence of a Lewis base. 18: The method of claim 17, wherein a molar ratio of the Lewis base to a polymerization initiator used for the anionic polymerization [(Lewis base)/(polymerization initiator)] is from 0.01 to 1,000. 19: The method of claim 17, wherein the Lewis base is a compound having at least one selected from the group consisting of an ether bond and a tertiary amino group in a molecule thereof. 20: The method of claim 17, wherein the Lewis base is a compound having one atom having an unshared electron pair. 21: The method of claim 17, wherein the Lewis base is a compound having two or more atoms having an unshared electron pair. 22: The method of claim 21, wherein the Lewis base has multidentate properties. 23: The method of claim 15, wherein a solid content concentration of a reaction liquid obtained after completion of the anionic polymerization is from 10 to 80% by mass. 24: The method of claim 15, wherein the anionic polymerization is carried out at −50 to 200° C. 25: The method of claim 15, wherein a conversion of the 1,3,7-octatriene after completion of the anionic polymerization, as determined by gas chromatography, is 80.0% or more. 26: The method of claim 15, wherein a conversion of the 1,3,7-octatriene after completion of the anionic polymerization, as determined by gas chromatography, is 88.0% or more. 